Radiographic image detector, radiographic imaging apparatus, radiographic imaging system

ABSTRACT

The present invention provides a radiographic image detector that may maintain even resolution in 6 directions before and after 3-pixel binning process or 4-pixel binning process. A radiation detector is disposed with plural pixels that have hexagonal shaped pixel regions, arrayed in a honeycomb pattern. Scan lines connected to TFT switches in each of the pixels are disposed one for each of the pixel rows. Grouped scan lines are also disposed one for each of the pixel rows for reading and combining 3 pixels or 4 pixels worth of charges at the same timing for plural pixel groups, each configured from 3 pixels or 4 pixels in a radiation detection element. ON signals are simultaneously sent by the grouped scanned lines to the TFT switches to perform 3-pixel binning or 4-pixel binning.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2011-282355, filed on Dec. 22, 2011, and Japanese PatentApplication No. 2012-267524, filed on Dec. 6, 2012 the disclosure ofwhich is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiographic image detector, aradiographic imaging apparatus and a radiographic imaging system. Thepresent invention particularly relates to a radiographic image detector,radiographic imaging apparatus and a radiographic imaging system fordirect conversion of radiation into charges.

2. Description of the Related Art

Recently, radiographic image detection apparatuses that have being putinto practice employ radiation detectors such as Flat Panel Detectors(FPDs) that have a X-ray-sensitive layer disposed above a Thin FilmTransistor (TFT) active matrix substrate, and are capable of directlyconverting X-ray data into digital data. Such FPDs have the advantage ofenabling more immediate image and video image confirmation than forexample conventional film screens, and their use is rapidly widening.Various types of radiation detectors are proposed, for example, thereare direct-conversion-type in which radiation is directly converted intocharges in a semiconductor layer and the charges accumulated, andindirect-conversion-type in which radiation is first converted intolight by a scintillator, such as CsI: Tl or GOS (Gd₂O₂S:Tb), and thenthe converted light is converted into charges in a semiconductor layerand the charges accumulated.

In radiation detectors, for example, plural scan lines and plural signallines are disposed intersecting with each other, and pixels are disposedin a matrix pattern corresponding to each of the intersections betweenthe scan lines and the signal lines. The plural scan lines and theplural signal lines are connected to an external circuit, such as, forexample an amplifier Integrated Circuit (IC) or a gate IC.

Reducing the size of the pixels in radiation detectors is an effectiveway to increase the resolution of FPDs. Particularly indirect-conversion-type radiation detectors employing for example Se,various radiation detectors are proposed for high definition enhancedimage quality, that contribute to increasing the resolution whilstleaving the pixel size virtually unchanged. For example, products withsmall pixel size are proposed for FPDs for mammography where there is anemphasis on resolution.

However, simply reducing the pixel size may lead to a drop insensitivity due to the proportional relationship to surface area in aradiation detection device. Accordingly, the use of hexagonal shapedpixels in radiation detection apparatuses in order to achieve anincrease in both resolution and sensitivity is proposed (see for exampleJapanese Patent Application Laid-Open (JP-A) No. 2003-255049). Further,with square shaped pixels, the resolution in diagonal directions islower than in the horizontal and vertical directions. However, employinghexagonal shaped pixels may secure high resolution in each of thehorizontal, vertical and diagonal directions.

When the use of the hexagonal shaped pixels described above in stillimaging and video imaging (fluoroscopic imaging) is considered, methodsof reading charges from plural pixels at the same time and summing theobtained values (binning) are being considered, in particular in orderto maintain a high frame rate such as in video. Performing such pixelsumming within a sensor is also being considered.

However, in pixel summing of plural hexagonal shaped pixels, unevennessin pixel positions (the positions of the center of gravity when pluralpixels are treated as one pixel cluster) may occur before and aftersumming, depending on the summing method. Accordingly, even resolutionin each of the horizontal, vertical and diagonal directions that hasbeen secured in before summing may not be maintained in after summing.

SUMMARY OF THE INVENTION

The present invention provides a radiographic image detector, aradiographic imaging apparatus and a radiographic imaging system thatmay maintain even resolution before and after combining the charges ofplural pixels in each of the horizontal, vertical and diagonaldirections.

A first aspect of the present invention is a radiographic image detectorincluding: a detection section including a plurality of pixels havinghexagonal shaped pixel regions arrayed in a honeycomb pattern, eachpixel including a sensor portion that generates charges according toirradiated radiation, a first switching element that reads out thegenerated charges, and a second switching element that reads out thegenerated charges; a plurality of first scan lines, disposed one foreach of a plurality of pixel rows configured by a plurality of thepixels adjacent to each other along a row direction, that are connectedto a control terminal of the first switching element in each of thepixels of the corresponding pixel row; and a plurality of second scanlines, disposed one for each of a plurality of pixel groups eachconfigured by a combination of a specific number of mutually adjacentpixels out of the plurality of pixels, that are connected to a controlterminal of the second switching element in each of the pixels in therespective pixel group so as to combine and read generated charges bypixel group unit, wherein the specific number of pixels are combinedsuch that, when a plurality of hexagonal shaped regions are placedadjacent to each other, the plurality of hexagonal shaped regions arearrayed in a honeycomb pattern, wherein each of hexagonal shaped regionsare formed by including one out of a plurality of centers of gravity ofthe plurality of pixel groups at the inside and line segments connectingtogether 6 individual centers of gravity present at the periphery of theone center of gravity.

A second aspect of the present invention is a radiographic imagedetector including: a detection section including a plurality of pixelshaving hexagonal shaped pixel regions arrayed in a honeycomb pattern,each pixel including, a sensor portion that generates charges accordingto irradiated radiation, a first switching element that reads out thegenerated charges, and a second switching element that reads out thegenerated charges; a plurality of first scan lines, disposed one foreach of a plurality of pixel rows configured by a plurality of thepixels adjacent to each other along a row direction, that are connectedto a control terminal of the first switching element in each of thepixels of the corresponding pixel row; a plurality of second scan lines,disposed one for each of the plurality of pixel rows, that are splitinto a plurality of line-groups and are connected to control terminalsof the second switching elements of the pixel groups belonging to eachrespective group such that, when combining and reading charges from aplurality of pixel groups each configured from a plurality of adjacentpixels in the plurality of pixel rows, charge signals corresponding tocombined charge amounts read out from the respective plurality of pixelgroups are transmitted through different respective data lines; and aplurality of data lines, disposed so as to respectively intersect withthe plurality of first scan lines and the plurality of second scanlines, that transmit first charge signals corresponding to charges readout by the first switching elements in each of the plurality of pixels,and that transmit second charge signals corresponding to the combinedcharge amounts read by the second switching elements of the respectiveplurality of pixel groups.

In a third aspect of the present invention, in the second aspect, eachof the plurality of pixel groups may be configured from 3 pixels,control terminals of the second switching elements of each of the pixelsin respective of the plurality of pixel groups alongside each other in arow direction may be respectively connected to the second scan lines,and adjacent scan lines may be commonly connected as a singleline-group.

In a fourth aspect of the present invention, in the third aspect, the 3pixels may be 3 pixels disposed such that two adjoining sides of each ofthe pixels are respectively adjacent to one side of each of the othertwo pixels.

In a fifth aspect of the present invention, in the second aspect, theplurality of pixel groups may be each configured by 4 pixels, the secondscan lines may be commonly connected in a line-group configured by anadjacent pair of the second scan lines, each pair of the second scanlines being configured by a second scan line connected to controlterminals of the second switching elements of 3 individual pixels in aplurality of respective pixel groups alongside each other in the rowdirection, and the second scan line connected to the control terminalsof the second switching elements of one individual pixel in each of theplurality of pixel groups.

In a sixth aspect of the present invention, in the fifth aspect, the 4pixels may be configured by 4 pixels made up from 3 pixels disposed suchthat two adjoining sides of each of the pixels are respectively adjacentto one side of the other 2 pixels out of the 3 pixels, and by 1 pixelmay be disposed such that two adjoining sides are respectively adjacentto one side of 2 pixels out of the 3 pixels.

In a seventh aspect of the present invention, in the second to the sixthaspects, the second switching elements may be connected to the pluralityof second scan lines are controlled as blocks with shifted timings foreach of the line-groups.

In an eighth aspect of the present invention, in the second to theseventh aspects, wherein combinations of the pixels configuringrespective pixel groups may be determined such that, when a plurality ofhexagonal shaped regions are formed adjacent to each other, theplurality of hexagonal shape regions results in a honeycomb patternarray, wherein each of the hexagonal shape regions may be formed byincluding inside one center of gravity of a region surrounded by anoutline of the plurality of pixel groups configured by the respective 3pixels or the respective 4 pixels, and by connecting together 6individual centers of gravity present at the periphery of the one centerof gravity.

In a ninth aspect of the present invention, in the above aspects, thehexagonal shaped pixel regions may be formed as regular hexagonalshapes.

In a tenth aspect of the present invention, in the first to the eighthaspects, the hexagonal shaped pixel regions may be formed as flattenedhexagonal shapes.

In an eleventh aspect of the present invention, in the tenth aspect, thehexagonal shaped pixel regions may be formed flattened such that onediagonal line out of 3 diagonal lines passing through the center of eachof the pixel regions is shorter than the other two diagonal lines andthe other two diagonal lines are of equal length to each other

In a twelfth aspect of the present invention, in the above aspects, theplurality of data lines may be laid out bent along one portion of thehexagonal shaped pixel region periphery.

In a thirteenth aspect of the present invention, in the above aspects,the sensor portions may include a semiconductor film that receivesirradiation with the radiation and generates charges, and the chargesmay be accumulated in a storage capacitor provided in each of theplurality of pixels and the charges accumulated in the storage capacitorare read by the first switching element and the second switchingelement.

In a fourteenth aspect of the present invention, in the first to thetwelfth aspects, the sensor portions may include a scintillator thatconverts the radiation that has been irradiated into visible light, andafter the converted visible light has been converted into charges by asemiconductor layer, the charges may be read out by the first switchingelement and the second switching element.

In a fifteenth aspect of the present invention, in the thirteenthaspect, may further include, a plurality of common lines that connecttogether one electrode of each of the storage capacitors and that fixesthe electrodes to a specific electrical potential.

In a sixteenth aspect of the present invention, in the fifteenth aspect,the plurality of common lines may extend between the plurality of datalines in a straight line shape or in a substantially straight lineshape.

In a seventeenth aspect of the present invention, in the sixteenthaspect, the plurality of common lines may be connected to the pluralityof data lines through the storage capacitors, the first switchingelements and the second switching elements.

In an eighteenth aspect of the present invention, in the seventeenthaspect, wherein the plurality of first scan lines, the plurality ofsecond scan lines, the plurality of data lines, the plurality of commonlines, the first switching elements, and the second switching elements,are disposed at a lower layer side of the sensor portions.

A nineteenth aspect of the present invention is a radiographic imagingapparatus including: the radiographic image detector of the aboveaspects; and a radiation irradiation section provided facing theradiographic image detector and that irradiates radiation onto animaging subject placed above the radiographic image detector, wherein aradiographic image is imaged with the radiographic image detector.

In a twentieth aspect of the present invention, in the nineteenthaspect, the radiation irradiation section may irradiate radiation ontothe imaging subject from each of a plurality of different imagingangles.

A twenty-first aspect of the present invention is a radiographic imagingsystem including: the radiographic imaging apparatus of the abovenineteenth and twentieth aspects; and control section that instructs theradiographic imaging apparatus to perform imaging of a radiographicimage, and that acquires a radiographic image from the radiographicimaging apparatus, wherein the control section includes, switchingsection that, based on an external instruction, switches between a firstradiographic image acquisition mode that acquires a first radiographicimage configured from image data in single-pixel units of a radiographicimage detection device, and a second radiographic image acquisition modethat acquires a second radiographic image configured from image data inmulti-pixel units of the radiographic image detection device.

In a twenty-second aspect of the present invention, in the twenty-firstaspect, when instructed to perform imaging to acquire the secondradiographic image, the control section may control the radiationirradiation section such that the radiation amount irradiated onto theimaging subject is an amount according to the multi-pixel unit andsmaller than when imaging to acquire the first radiographic image.

A twenty-third aspect of the present invention is a radiographic imagingsystem including: the radiographic imaging apparatus of the twentiethaspect; control section that instructs the radiographic imagingapparatus to perform imaging of a radiographic image, and that acquiresa plurality of radiographic images from the radiographic image detectorthat have been imaged by the radiographic image detector at each of theimaging angles; and tomographic image generation section that generatesa plurality of tomographic images reconstructed with reference to adetection face of the radiographic image detector based on the pluralityof radiographic images acquired by the control section; wherein thecontrol section includes, switching section that, based on an externalinstruction, switches between a first radiographic image acquisitionmode that acquires a first radiographic image configured from image datain single-pixel units of a radiographic image detection device, and asecond radiographic image acquisition mode that acquires a secondradiographic image configured from image data in multi-pixel units ofthe radiographic image detection device, and wherein the radiationirradiation section has a range of image angles for irradiatingradiation onto the imaging subject that is larger when imaging toacquire the first radiographic image than when imaging to acquire thesecond radiographic image.

In a twenty-second aspect of the present invention, in the twenty-firstaspect, the thickness of the tomographic image generated by thetomographic image generation section based on the first radiographicimages may be thinner than the thickness of the tomographic imagesgenerated based on the second radiographic images.

Thus according to the above aspects, the present invention may imageradiographic images at a fast rate, and may maintain even resolution ineach of the horizontal, vertical and diagonal directions, before andafter charge binning of pixel groups configured by plural pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described indetail based on the following figures, wherein:

FIG. 1 is a block diagram illustrating a configuration of a radiographicimaging system according to a first exemplary embodiment of the presentinvention;

FIG. 2 is a drawing illustrating an electrical configuration of aradiation detector of an imaging apparatus according to the firstexemplary embodiment;

FIG. 3 is a drawing illustrating a partial cross-sectional view of aradiation detection device of a radiation detector according to thefirst exemplary embodiment;

FIG. 4 is a drawing illustrating a layout of pixels and pixel groupssubject for binning in the first exemplary embodiment;

FIG. 5 is a flow chart showing an example of an imaging processingsequence of a radiographic imaging system according the first exemplaryembodiment;

FIG. 6 is a drawing illustrating an electrical configuration of aradiation detector of an imaging apparatus according to a secondexemplary embodiment of the present invention;

FIG. 7 is a drawing illustrating a layout of pixels and pixel groupssubject for binning in the second exemplary embodiment;

FIG. 8 is a drawing illustrating an electrical configuration of aradiation detector of an imaging apparatus according to a thirdexemplary embodiment of the present invention;

FIG. 9 is a drawing illustrating a layout of pixels and pixel groupssubject to binning in the third exemplary embodiment;

FIG. 10 is a drawing illustrating an electrical configuration of aradiation detector of an imaging apparatus according to a fourthexemplary embodiment of the present invention;

FIG. 11 is an operation timing chart of a radiation detector duringbinning processing of the fourth exemplary embodiment;

FIG. 12 is a drawing illustrating a simplified example of a radiationdetector of the first exemplary embodiment applied to anindirect-conversion-type radiation detector;

FIG. 13 is a drawing illustrating a simplified example of a radiationdetector of the third exemplary embodiment applied to anindirect-conversion-type radiation detector;

FIG. 14 is a schematic configuration diagram illustrating aconfiguration of an imaging apparatus for mammography of a fifthexemplary embodiment of the present invention;

FIG. 15 is a configuration diagram illustrating a configuration of animaging apparatus according to the fifth exemplary embodiment duringimaging;

FIG. 16 is an explanatory diagram to explain an imaging apparatusaccording to the fifth exemplary embodiment during imaging; and

FIG. 17 is a flow chart illustrating a sequence of processing forimaging an image in a radiographic imaging system according to the fifthexemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Explanation follows regarding exemplary embodiments of the presentinvention, with reference to the drawings.

First Exemplary Embodiment

FIG. 1 is a block diagram illustrating a configuration of a radiographicimaging system 100 according to a first exemplary embodiment of thepresent invention. The radiographic imaging system 100 includes animaging apparatus 41 that images radiographic images, an imageprocessing apparatus 50 that performs image processing on image dataexpressing imaged radiographic images, and a display device 80 fordisplaying an image expressed by the image data that has been subjectedto image processing.

The imaging apparatus 41 includes a radiation irradiation section 24, aradiation detector 42 that detects a radiographic image, an operationpanel 44 that is input with exposure conditions including data, such as,tube voltage, tube current, irradiation duration, imaging conditions,various operation data and various operation instructions, an imagingapparatus control section 46 that controls the operation of theapparatus overall, a display 47 that displays such displays as anoperation menu and various information, and a communication I/F section48 that is connected to a network 56 such as a LAN and that transmitsand receives various data to and from other devices connected to thenetwork 56. The imaging apparatus 41 according to the present exemplaryembodiment is configured capable of switching between a video imagingmode that successively images radiographic images (video imaging) and astill imaging mode that performs still imaging. The imaging mode can beinput as one of the imaging conditions to the imaging apparatus 41 fromthe operation panel 44. The imaging apparatus 41 performs video imagingor still imaging according to the imaging mode input through theoperation panel 44.

The imaging apparatus control section 46 includes a CPU 46A, ROM 46B,RAM 46C and a non-volatile storage section 46D configured, for example,from a HDD or flash memory. The imaging apparatus control section 46 isconnected to the radiation irradiation section 24, the radiationdetector 42, the operation panel 44, the display 47 and thecommunication I/F section 48 through a bus (not shown in the drawings).Programs, such as a program for execution by the CPU 46A, are stored inthe storage section 46D. Data such as image data (digital data)expressing radiographic images is stored in the storage section 46D. Forexample, when the imaging apparatus 41 of the present exemplaryembodiment is employed for mammography, radiographic image data obtainedby imaging the breast of a subject is stored in the storage section 46D.

When irradiated with radiation from the radiation source 31 of theradiation irradiation section 24 according to the exposure conditions,the radiation detector 42 detects the radiation and outputs image dataexpressing a radiographic image to the imaging apparatus control section46. Details regarding the configuration of the radiation detector 42 aregiven later.

The imaging apparatus control section 46 is capable of communicatingwith the image processing apparatus 50 through the communication I/Fsection 48 and the network 56, and the imaging apparatus control section46 performs transmission and reception of various data to and from theimage processing apparatus 50. A management server 57 is also connectedto the network 56. The management server 57 is configured including astorage section 57A that stores specific management data. The imagingapparatus control section 46 is enabled for communication with themanagement server 57 through the communication I/F section 48 and thenetwork 56.

The image processing apparatus 50 is configured as a server computer andincludes a display 52 that displays for example an operation menu andvarious data, and an operation input section 54 configured includingplural keys for inputting various data and operation instructions. Theimage processing apparatus 50 includes a CPU 60 for controlling theapparatus operation overall, ROM 62 that is pre-stored with variousprograms including a control program, RAM 64 for temporary storage ofvarious data, a HDD 66 for storing and retaining various data, a displaydriver 68 for controlling the display of various data on the display 52,an operation input detection section 70 for detecting operation stateswith respect to the operation input section 54, a communication I/Fsection 72 that is connected to the imaging apparatus 41 through thenetwork 56 and that performs transmission and reception of various datato and from the imaging apparatus 41, and an image signal output section74 that outputs image data through a display cable 58 to the displaydevice 80. The image processing apparatus 50 acquires image data(digital data) expressing radiographic images stored in the storagesection 46D from the imaging apparatus 41, via the communication OFsection 72.

The CPU 60, the ROM 62, the RAM 64, the HDD 66, the display driver 68,the operation input detection section 70, the communication I/F section72 and the image signal output section 74 are mutually connected througha system BUS. The CPU 60 is accordingly able to access the ROM 62, theRAM 64 and the HDD 66. The CPU 60 is capable of performing variouscontrol, such as controlling display of various data on the display 52through the display driver 68, controlling transmission and reception ofvarious data to and from the imaging apparatus 41 through thecommunication I/F section 72, and controlling image display on a displaysection 80A of the display device 80 through the image signal outputsection 74. The CPU 60 is also capable of ascertaining user operationstates to the operation input section 54 through the operation inputdetection section 70.

FIG. 2 illustrates an electrical configuration of a radiation detectorof an imaging apparatus according to the present exemplary embodiment. Aradiation detection element 10 of the radiation detector 42 illustratedin FIG. 2 is configured with plural pixels 20 that have hexagonal shapedpixel regions arrayed adjacently in a two dimensional honeycomb pattern,so as to configure a region that is substantially rectangular shapedoverall. Each of the pixels 20 is configured including a sensor portion103 that receives radiation (X-rays) that has been irradiated andgenerates charges, a charge storage capacitor 5 that accumulates thecharges that have been generated in the sensor portion 103, and two thinfilm transistors (hereinbelow referred to as TFT switches) 4 a, 4 b forreading the charges accumulated in the charge storage capacitors 5. Theradiation detector 42 is accordingly a direct-conversion-type radiationdetector that employs a radiation—charge conversion material, such asamorphous selenium in a photoelectric conversion layer, to absorbradiation and convert it into charges, as described later.

Disposing the pixels 20 in a honeycomb pattern means that the pixels 20having hexagonal shaped pixel regions of the same size as each other arearrayed with plural first pixel rows arrayed in a row direction (thehorizontal direction in FIG. 2), and plural second pixel rows,configured by pixels 20 having hexagonal shaped pixel regions of thesame size as the first pixel row pixels 20 arrayed in the row direction.The first pixel rows and the second pixel rows are arrayed alternatelyalong a direction that intersects with a column direction (the verticaldirection in FIG. 2). The pixels 20 of the second pixel rows aredisposed aligned between adjacent pixels of the first pixel rows, suchthat the pixels 20 of the second pixel rows are displaced in the rowdirection from the pixels 20 in the first pixel rows by ½ the arraypitch of the first pixel row pixels 20.

The radiation detector 42 includes first scan lines G1-0 to G1-7 (alsoreferred to as first scan lines G1, further also referred collectivelyto as scan lines G when referred together with the below mentioned scanlines) disposed corresponding to each of the pixel rows. The gateelectrodes of the TFT switches 4 a provided in each of the pixels 20 areconnected to the first scan lines G1, and the TFT switches 4 a areON/OFF controlled according to signals flowing in the first scan linesG1. The radiation detector 42 is also equipped with second scan linesG2-0 to G2-3 (also referred to as second scan lines G2) disposedcorresponding to each of the pixel rows equipped with the first scanlines G1-0 to G1-3, and with third scan lines G3-0 to G3-3 (alsoreferred to as third scan lines G3) disposed corresponding to each ofthe pixel rows equipped with the first scan lines G1-4 to G1-7. The gateelectrodes of the TFT switches 4 b provided in pixels configuring pixelgroups, are connected to the second scan lines G2 and the third scanlines G3, and the TFT switches 4 b are ON/OFF controlled according tosignals flowing in the second scan lines G2 and the third scan lines G3.

Accordingly, the radiation detection element 10 of the radiationdetector 42 is configured with pixel rows disposed with one of the firstscan lines G1 and one of the second scan lines G2, and with pixel rowsdisposed with one of the first scan lines G1 and one of the third scanlines G3. The radiation detector 42 is also equipped with plural datalines D1 to D6 (also referred to collectively as data lines D) forreading the charges that were generated in the sensor portions 103 ineach of the pixels and accumulated in the respective charge storagecapacitors 5, and with common ground lines 30.

Note that the sensor portions 103 of each of the pixels 20 areconfigured connected to common lines (not shown in the drawings) so asto be applied with a bias voltage from a power supply (not shown in thedrawings) through the common lines. Moreover, although FIG. 2illustrates a configuration in which the second scan lines G2-0 to G2-3and the third scan lines G3-0 to G3-3 respectively branch from a singleline extending out from a scan signal control section 35 into fourlines, there is no limitation thereto. For example, configuration may bemade such that each of the second scan lines G2-0 to G2-3 and the thirdscan lines G3-0 to G3-3 extend out separately from the scan signalcontrol section 35, and the second scan lines G2-0 to G2-3 are drivensimultaneously and then the third scan lines G3-0 to G3-3 are drivensimultaneously.

Configuration may also be made with a second scan signal control sectionprovided separately to the scan signal control section 35, such that 1line extending out from the second scan signal control section branchesinto 4. Further, configuration made such that there are separateindividual second scan lines G2-0 to G2-3 and third scan lines G3-0 toG3-3 extending out from the second scan signal control section providedseparately to the scan signal control section 35, with the second scanlines G2-0 to G2-3 driven simultaneously and the third scan lines G3-0to G3-3 driven simultaneously. Note that, although the drive load islarge in a configuration with a single line branching into 4, there isthe advantage that a second scan signal control section does not have tobe provided, and a configuration respectively connected to a separatesecond scan signal control section has the advantage that the drive loadis small.

In FIG. 2, for ease of explanation and illustration, an example is shownof a configuration laid out with 14 scan lines G and 6 data lines D. Ingeneral, when, for example, there are m×n individual pixels 20respectively disposed in the row direction and the column direction(wherein m and n are positive integers), there are 2m scan lines and ndata lines provided.

In the radiation detector 42, the scan lines G1 to G3 are disposed so asto intersect with the data lines D and the common ground lines 30. Thedata lines D are laid out along the peripheral edges of the pixels 20with hexagonal shaped pixel regions in a zigzag pattern (so as tomeander) so as to bypass these pixels 20. Namely, the data lines Dextend in the column direction while running along 3 adjoining sides outof the peripheral edges (6 sides) of each of the individual pixels 20.

In the radiation detector 45 of the present exemplary embodiment, if,for example, the common ground lines 30 are also disposed in a zigzagpattern (so as to meaner) to match the data lines D, there is thepossibility of various issues such as, for example, locations where theseparation between TFT switches 4 a, 4 b in the pixels 20 is narrowoccurring at portions meandering to the left or right, common groundlines 30 and TFT switches 4 a and 4 b colliding, and/or the capacitybetween data lines D and the common ground lines 30 increasing. Theradiation detector 42 of the present exemplary embodiment is therefore,as illustrated in FIG. 2, laid out with the plural scan lines G1 to G3running along a row direction (the horizontal direction in FIG. 2)arrayed parallel to each other, and the plural data lines D1 to D6disposed extending along a column direction (the vertical direction inFIG. 2) so as to intersect with the scan lines G1 to G3 and to bendaround along the peripheral edges of pixels 20.

The TFT switches 4 a, 4 b etc., inside each of the pixels 20, are alsolaid out towards one side so as to secure specific free spaces in eachof the pixels 20, and the common ground lines 30 are laid out so as topass through these free spaces. For example, the TFT switches 4 a, 4 betc. are disposed in regions surrounded by a line segment thatpartitions each of the pixels 20 in half along the column direction (thevertical direction in FIG. 2) and 3 sides at the periphery of each ofthe pixels 20 where the data lines D are provided. Namely, the TFTswitches 4 a, 4 b etc. are laid out in the region of the right hand halffor pixels in a given pixel row, and the TFT switches 4 a, 4 b etc. arelaid out in the region of the left hand half for pixels 20 in the pixelrow positioned above and below the given pixel row in the columndirection.

Accordingly, the common ground lines 30 may be disposed as straightlines intersecting with the scan lines G1 to G3 between the plural datalines D1 to D6 and without intersecting with the data lines D1 to D6.Hence, the storage capacitor lower electrodes 11 of the charge storagecapacitors 5 of each of the pixels 20 can be mutually connected togetherby the shortest common ground lines 30, in a direct-conversion-typeradiographic image detector 42. The need to make the common ground lines30 meander to match the data lines D is also eliminated. Since there isalso no intersection between the data lines D and the common groundlines 30, an increase in noise caused by such effects as induction inthe data lines, and an increase in the interline capacitance between thedata lines D and the common ground lines 30, may not occur.

The resolution of the radiation detection device can also be raisedwithout the straight line common ground lines 30 impeding higherdefinition of pixels 20 of the radiation detection element 10. Moreover,in the manufacturing processes for the radiation detection element 10, adrop in manufacturing yield of the radiation detection device due tointerline pitch between the data lines D and the common ground lines 30narrower, may be avoided. Note that, disposing the common ground lines30 as straight lines means that a straight state is maintained within arange obtainable while allowing for manufacturing error in manufacturingprocesses of the radiation element 10.

When imaging a radiographic image with the radiation detector 42, duringirradiation with external radiation (X-rays) OFF signals are output tothe first scan lines G1 and each of the TFT switches 4 a is switchedOFF, and OFF signals are output to the second scan lines G2 and thethird scan lines G3, switching each of the TFT switches 4 b OFF. Thecharges generated in a semiconductor layer are accordingly accumulatedin each of the charge storage capacitors 5.

When reading an image, for example a still image, ON signals are outputin sequence one line at a time to the first scan lines G1-0 to G1-7,switching the TFT switches 4 a in each of the pixels 200N. Or, forexample when reading a video image, ON signals are output simultaneouslyto the second scan lines G2-0 to G2-3 and then ON signals are outputsimultaneously to the third scan lines G3-0 to G3-3, switching ON theTFT switches 4 b of plural pixels in pixel groups. The chargesaccumulated in each of the charge storage capacitors 5 are thereby readas electrical signals, and a radiographic image is obtained byconverting the read electrical signals into digital data.

A signal processing section 25 includes signal detectors (not shown inthe drawings) that detect charges flowing out of each of the data linesD1 to D6 as electrical signals, and subjects the detected electricalsignals to specific processing. The signal processing section 25 alsooutputs control signals expressing a signal detection timing to thesignal detectors and control signals expressing a scan signal outputtiming to the scan signal control section 35. As a result, on receipt ofthe control signals from the signal processing section 25, the scansignal control section 35 outputs signals to the first scan lines G1-0to G1-7 for switching the TFT switches 4 a ON/OFF. The scan signalcontrol section 35 also outputs signals to the second scan lines G2-0 toG2-3 and the third scan lines G3-0 to G3-3 for switching the TFTswitches 4 b ON/OFF.

The charge signals transmitted by the individual data lines D1 to D3 areamplified in the signal processing section 25 by amplifiers, and areheld in sample-and-hold circuits (not shown in the drawings). The chargesignals held by the individual sample-and-hold circuits are input insequence to a multiplexer (not shown in the drawings), and thenconverted into digital image data by an A/D converter. Note that animage memory 90 is connected to the signal processing section 25, andthe digital image data output from the A/D converter is stored insequence in the image memory 90. The image memory 90, for example,stores digital image data for plural frames worth of imaged radiographicimages.

FIG. 3 illustrates a partial cross-sectional view including a singlepixel of a radiation detection element 10 of a radiation detector 42according to the first exemplary embodiment. The radiation detectionelement 10 of the radiation detector 42 is, as shown in FIG. 3, astructure in which gate electrodes 2, scan lines G (not shown in FIG. 3)and storage capacitor lower electrodes 14 are formed as a gate wiringlayer on an insulating substrate 1. A wiring layer (also referred to asa source wiring layer) formed with source electrodes 9, drain electrodes13, data lines D, and storage capacitor upper electrodes 16 is formedusing a layered film of, for example, Al or Cu, or mainly of Al or Cu.An impurity doped semiconductor layer (not shown in the drawings) suchas impurity doped amorphous silicon is formed between semiconductoractive layers 8 and the source electrodes 9, and the drain electrodes13. Note that the source electrodes 9 and the drain electrodes 13 arereversed in the TFT switches 4 a, 4 b according to the polarity of thecharges collected and accumulated by a lower electrode 11.

The gate wiring layer for the gate electrodes 2 is formed using alayered film of, for example, Al or Cu, or mainly of Al or Cu. Aninsulating film 15A is formed on one face on the gate wiring layer, andthe locations of the insulating film 15A above the gate electrodes 2 actas gate insulation films for the TFT switches 4 a, 4 b. The insulatingfilm 15A is, for example, configured from SiNx, and is formed, forexample, by a Chemical Vapor Deposition (CVD) film forming process. Thesemiconductor active layers 8 are formed with island shapes on theinsulation film 15A above each of the gate electrodes 2. Thesemiconductor active layers 8 are channel portions of the TFT switches 4a, 4 b and are, for example, formed from an amorphous silicon film.

The source electrodes 9 and the drain electrodes 13 are formed in alayer above the gate electrodes 2. In the wiring layer in which thesource electrodes 9 and the drain electrodes 13 are formed, the datalines D are also formed together with the source electrodes 9 and thedrain electrodes 13. The storage capacitor upper electrodes 16 are alsoformed at positions on the insulating film 15A corresponding to thestorage capacitor lower electrodes 14. The drain electrodes 13 areconnected to the storage capacitor upper electrodes 16. The data lines Dare disposed running along the peripheral edges of the pixels 20 in themanner described above, bent so as to bypass between one pixel and anadjacent pixel. The data lines 3 are connected to the source electrodes9 formed to the pixels 20 in each of the pixel rows.

A TFT protection layer 15B is formed over substantially the wholesurface (substantially all regions) of the region where the pixels areprovided on the substrate 1 so as to cover the source wiring layer. TheTFT protection layer 15B is formed, for example, from a material such asSiN), by, for example, a CVD film forming method. A coated interlayerinsulating film 12 is then formed on the TFT protection layer 15B. Theinterlayer insulating film 12 is formed from a low permittivity(specific permittivity ε_(r)=2 to 4) photosensitive organic material(examples of such materials include positive working photosensitiveacrylic resin materials with a base polymer formed by copolymerizingmethacrylic acid and glycidyl methacrylate, mixed with a naphthoquinonediazide positive working photosensitive agent) at a film thickness of 1μm to 4 μm.

In the radiation detection element 10 of the radiation detector 42according to the present exemplary embodiment, inter-metal capacitancebetween metal disposed in the layers above the interlayer insulatingfilm 12 and below the interlayer insulating film 12 is suppressed to besmall by the interlayer insulating film 12. Generally the materials ofthe interlayer insulating film 12 also function as a flattening film,exhibiting an effect of flattening out steps in the layers below. In theradiation detection element 10 of the radiation detector 42, contactholes 17 are formed in the interlayer insulating film 12 and the TFTprotection layer 15B at locations corresponding to the storage capacitorupper electrodes 16.

Lower electrodes 11 of each of the sensor portions 103 are formed on theinterlayer insulating film 12 for each of the pixels 20, so as to coverthe pixel region while also filling each of the contact holes 17. Thelower electrodes 11 are formed from an amorphous transparent conductingoxide film (ITO) and are connected to the storage capacitor upperelectrodes 16 through the contact holes 17. As a result, the lowerelectrodes 11 and the TFT switches 4 a, 4 b are electrically connectedthrough the storage capacitor upper electrodes 16. Note that while thelower electrodes 11 are preferably formed in shapes to match the shapesof the pixel regions of the pixels 20, there is no limitation thereto.For example, when the pixel regions of the pixels 20 are regularhexagonal shaped, the lower electrodes 11 are preferably formed withslightly smaller regular hexagonal shapes so as not to touch the lowerelectrodes of adjacent pixels. Similarly, when the pixel regions of thepixels 20 are formed in flattened hexagonal shapes the lower electrodes11 are preferably formed in slightly smaller hexagonal shapes. As longas the pixel placement of the lower electrodes configures a hexagonallattice, configuration may be made with beveled corner hexagonal shapedor square shaped lower electrodes 11.

A photoelectric conversion layer 6 is uniformly formed on the lowerelectrodes 11 over substantially the entire surface of the pixel regionwhere the pixels 20 are provided on the substrate 1. The photoelectricconversion layer 6 generates charges (electrons-holes) internally onirradiation with radiation such as X-rays. In other words, thephotoelectric conversion layer 6 has electrical conduction propertiesand is employed to convert image data from radiation into charge data.For example, the photoelectric conversion layer 6 may be formed fromamorphous selenium (a-Se) having selenium as the main component and afilm thickness of 100 μm to 1000 μm. Note that, the main component meanscontained at a ratio of 50% of more. An upper electrode 7 is formed onthe photoelectric conversion layer 6. The upper electrode 7 is connectedto a bias power source (not shown in the drawings) and supplies a biasvoltage (for example several kV) from the bias power source. The pluralscan lines G1, G2, G3, the data lines 3, the common ground lines 30 andthe TFT switches 4 a, 4 b are disposed at a lower layer side of thesensor portions 103 configured by the photoelectric conversion layer 6.

In the radiation detection element 10 of the radiation detector 42, thegate electrodes 2, the first to the third scan lines G1 to G3 and thestorage capacitor lower electrodes 14 are formed as the gate wiringlayer on the substrate 1, and the common ground lines 30 are formed onthe substrate 1, for example in the same metal layer as the storagecapacitor lower electrodes 14.

Explanation next follows regarding operation of the radiation detector42 according to the present exemplary embodiment. Charges (electron-holepairs) are generated in the photoelectric conversion layer 6 when X-raysare irradiated onto the photoelectric conversion layer 6 in a state inwhich a bias voltage is being applied across the upper electrode 7 andthe storage capacitor lower electrodes 14. The photoelectric conversionlayer 6 and the charge storage capacitors 5 are electrically connectedin series, and so electrons generated in the photoelectric conversionlayer 6 migrate to the +(plus) electrode side and holes migrate to the−(minus) electrode side.

During image detection, OFF signals (for example, 0V) are output fromthe scan signal control section 35 to the first scan lines G1-0 to G1-7,the second scan lines G2-0 to G2-3 and the third scan lines G3-0 toG3-3, applying a negative bias to the gate electrodes of the TFTswitches 4 a, 4 b. Each of the TFT switches 4 a, 4 b are therebymaintained in an OFF state. As a result, electrons generated in thephotoelectric conversion layer 6 are collected by the lower electrodes11, and are accumulated in the charge storage capacitors 5. Thephotoelectric conversion layer 6 generates a charge amount according tothe amount of radiation irradiated, and so the charges according toimage data carried by the radiation are accumulated in the chargestorage capacitors 5 of each of the pixels. Note that the charge storagecapacitors 5 need to be given a larger capacitance than the capacitanceformed by the photoelectric conversion layer 6 due to the voltage ofseveral kV referred to above being applied across the upper electrode 7and the storage capacitor lower electrodes 14.

During image reading, the radiation detector 42 performs in a stillimaging mode or a video imaging mode according to instruction from theimage processing apparatus 5.0 as described above. When instruction wasfor the still imaging mode, the signal processing section 25 controlsthe scan signal control section 35 such that scan signals are outputfrom the second scan lines G2-0 to G2-3 and the third scan lines G3-0 toG3-3 for switching OFF the TFT switches 4 b in each of the pixels 20.The signal processing section 25 also controls the scan signal controlsection 35 to apply ON signals for example with a voltage of +10 V to 20V in sequence from the first scan lines G1-0 to G1-7 to the gates ofeach of the TFT switches 4 a in order to switch ON the TFT switches 4 ain each of the pixels 20. The TFT switches 4 a in each of the pixels 20are thereby switched to an ON state in sequence for each of the pixelrows, charges are read from the sensor portions 103 by the TFT switches4 a, and signals corresponding to these charges are output to the datalines D.

Thus in the radiation detector 42, in the still imaging mode, in all ofthe data lines D1 to D6 charge signals flow corresponding to each of thepixels 20 in each of the pixel rows. Accordingly, image data expressingan image representing radiation irradiated onto the radiation detectionelement 10 of the radiation detector 42 can be obtained. In the signalprocessing section 25, the charge signals are then converted intodigital signals, and a radiographic image based on the image datacorresponding to the charge signals is generated.

Explanation follows regarding the video imaging mode. In the radiationdetector 42 according to the present exemplary embodiment, out of theplural pixels 20 illustrated in FIG. 2, for example, the 4 pixels P0 toP3 form a pixel group PG0, the 4 pixels P4 to P7 form a pixel group PG1,the 4 pixels P8 to P11 form a pixel group PG2, the 4 pixels P12 to P15form a pixel group PG3, the 4 pixels P16 to P19 form a pixel group PG4.In these 5 pixel groups, the gate electrodes of each of the TFT switches4 b in, the pixel P0 of the pixel group PG0, the pixel P4 of the pixelgroup PG1 and the pixel P8 of the pixel group PG2, are connected to thesecond scan line G2-0. The gate electrodes of each of the TFT switches 4b in, the pixels P1 to P3 of the pixel group PG0, the pixels P5 to P7 ofthe pixel group PG1, and the pixels P9 to P11 of the pixel group PG2,are connected to the second scan line G2-1.

Similarly, the gate electrodes of each of the TFT switches 4 b in, thepixel P12 of the pixel group PG3, and the pixel P16 of the pixel groupPG4, are connected to the second scan line G2-2, and the gate electrodesof each of the TFT switches 4 b in, the pixels P13 to P15 of the pixelgroup PG3, and the pixels P17 to P19 of the pixel group PG4, areconnected to the second scan line G2-3. In the radiation detectionelement 10, connections of the pixel groups, (PG5 to PG9) configured bythe pixels P20 to P23, the pixels P24 to P27, the pixels P28 to P31, thepixels P32 to P35, and the pixels P36 to P39, and the third scan linesG3-0 to G3-3, are connected in a similar pattern to the connectionsdescribed above of the pixel groups PG0 to PG4 to the second scan linesG2-0 to G2-3.

When the video imaging mode is instructed to the radiation detector 42,the signal processing section 25 controls the scan signal controlsection 35 so as to switch OFF the TFT switches 4 a of each of thepixels 20, and outputs OFF signals from the first scan lines G1-0 toG1-7 to each of the gate electrodes of the TFT switches 4 a of each ofthe pixels 20.

The signal processing section 25 also controls the scan signal controlsection 35 to simultaneously drive the second scan lines G2-0 to G2-3 tooutput scan signals (ON signals). The TFT switches 4 b of all the pixels20 in the pixel groups PG0 to PG4 are switched ON when the ON signal isoutput simultaneously to the second scan lines G2-0 to G2-3. As aresult, the charges accumulated in each of the charge storage capacitors5 of the four individual pixels P0 to P3 of the pixel group PG0 arecombined and the combined charge signal is output to the data line D2.Similarly, a combined charge signal of the four individual pixels P12 toP15 of the pixel group PG3 is output to the data line D3, a combinedcharge signal of the four individual pixels P4 to P7 of the pixel groupPG1 is output to the data line D4, a combined charge signal of the fourindividual pixels P16 to P19 of the pixel group PG4 is output to thedata line D5, and a combined charge signal of the four individual pixelsP8 to P11 of the pixel group PG2 is output to the data line D6.

Then the signal processing section 25 controls the scan signal controlsection 35 to simultaneously drive the third scan lines G3-0 to G3-3 andoutput scan signals (ON signals) thereto. The TFT switches 4 b of allthe pixels 20 in the pixel groups PG5 to PG9 are switched ON when the ONsignals are simultaneously output to the third scan lines G3-0 to G3-3.As a result a combined charge signal from the four pixels of the pixelgroup PG5 is output to the data line D2, a combined charge signal of thefour pixels of the pixel group PG8 is output to the data line D3, acombined charge signal of the four pixels of the pixel group PG6 isoutput to the data line D4, a combined charge signal of the four pixelsof the pixel group PG9 is output to the data line D5, and a combinedcharge signal of the four pixels of the pixel group PG7 is output to thedata line D6.

Thus, when in the video imaging mode, in each of the plural pixel groupsconfigured by four pre-specified pixels from the plural pixels 20configuring the radiation detection element 10, the charges accumulatedin the four individual pixels are combined (binned) and a charge signalcorresponding to the binned charges is output to the respective datalines. This means that when performing video imaging, due to performingbinning processing at 2 pixels×2 pixels imaging may be performed at 4times the rate of the still imaging mode.

As described above, the binning scan lines G (G2 and G3) are split intoplural groups (G2 and G3), and scan signals for the TFT switch 4 b aresent to the scan lines G belonging to each of the groups at timingsshifted for each of the groups. Hence, when combining and reading thecharges of the plural pixel groups at each timing, the charge signalscorresponding to the combined charge amounts read from different pixelgroups are not transmitted through the same data lines D.

FIG. 4 illustrates a layout of pixels and pixel groups subject tobinning in the video imaging mode described above. Note that, in FIG. 4,the shading pattern has been changed for each of the pixels in adjacentpixel groups to make it easier to discriminate the respective pixelgroups from each other.

In the example illustrated in FIG. 4, the radiation detection element 10of the radiation detector 42 specifies pixel groups A, B, C, D, E, F, Gformed from 4 adjacent pixels as described above. Each of the pixelgroups are configured from 4 pixels, configured by a first pixel out ofthe plural pixels, a second pixel and a third pixel that are eachmutually adjacent to each other in a row adjacent to the first pixelrow, and a fourth pixel that is in a row adjacent to the second pixeland third pixel row. The 4 pixels are disposed such that two adjoiningsides of the first pixel and two adjoining sides of the fourth pixel arerespectively adjacent to one side of the second pixel and the thirdpixel, respectively, so as to lie between the second pixel and the thirdpixel.

In other words, each of the pixel groups can be defined as being acombination of 4 pixels configured by 3 pixels, disposed such that twoadjoining sides of each of the pixels are respectively mutually adjacentto one side of the remaining 2 pixels, and by 1 pixel, disposed suchthat two adjoining sides are respectively mutually adjacent to one sideof 2 pixels out of the 3 pixels. The combination of 4 pixels may also bedescribed as being a combination of 4 pixels formed from 2 pairs ofmutually adjacent pixels disposed alongside each other, with 2 adjoiningsides of 1 pixel from a first pair disposed mutually adjacent to 1 sideof each of the 2 pixels in the other pair respectively.

When still imaging mode is instructed as described above in theradiation detector 42 of the present exemplary embodiment, the signalprocessing section 25 switches ON the TFT switches 4 a in each of thepixels 20 of the radiation detector 42, reads out the charges from eachof the pixels, and outputs signals corresponding to the charges to thedata lines D. Since pixels with hexagonal shaped pixel regions areemployed as the individual pixels in the radiation detection element 10of the radiation detector 42 of the present exemplary embodiment, a highresolution may be secured in each of the horizontal, vertical anddiagonal directions.

However, in the video imaging mode, due to the signal processing section25 switching ON the TFT switches 4 b inside 4 pixels configuring each ofthe pixel groups as described above, the 4 pixels act as a single pixel,and binning is performed to combine 4 pixels worth of charges. Note thatin FIG. 4, the positions of the center of gravity for each of the pixelgroups A, B, C, D, E, F, G formed from 4 pixels are positioned as blackdots indicated respectively as a, b, c, d, e, f, g.

In the example indicated in FIG. 4, when performing 4 pixel binning foreach of the pixel groups, a regular hexagonal shape is formed byconnecting the centers of gravity of other pixel groups a-b-e-g-f-c-a,with the center of gravity d of the pixel group D at the center. It canalso be seen that the inter center of gravity distances of these pixelgroups, namely in the 6 directions d to a, d to b, d to e, d to g, d tof, and d to c, are all the same as each other. Thus by making each ofthe pixels 20 a hexagonal shape, even resolution may be secured in eachof the horizontal, vertical and diagonal directions, before binning.Moreover, since a regular hexagonal shape is also formed by connectingtogether the centers of gravity of the pixel groups, even resolution mayalso be secured in each of the horizontal, vertical and diagonaldirections, after binning.

Namely, the combinations of each of the pixels in each of the pixelgroups are determined such that plural hexagonal shaped regions arearrayed in a honeycomb pattern. By employing, for example, the center ofgravity a, b, c, d, e, f, g of each of the regions surrounded by theoutlines of the pixel groups A, B, C, D, E, F, G, each of the hexagonalshaped regions are formed including, 1 center of gravity d at theinside, and hexagonal shaped region formed by the line segmentsconnecting the 6 individual centers of gravity a, b, e, g, f, c presentat the periphery of the center of gravity d. Accordingly, the presentexemplary embodiment may suppress unevenness in each of the horizontal,vertical and diagonal directions of the pixel positions (the center ofgravity positions of the pixel groups) after binning, and may enableeven resolution to be secured in each of the respective directions,similarly to in an image before binning.

Since the centers of gravity arrayed before binning, and the hexagonalshaped regions formed by the centers of gravity arrayed after binning,are both arrayed in a honeycomb pattern, processing may be performedwith a similar algorithm when performing pixel density conversion afterbinning, to when performing pixel density conversion without binning.Namely, the algorithm for pixel density conversion processing may becommonly employed both before and after binning, without preparinganother separate algorithm for pixel density conversion processing afterbinning. In the image processing apparatus 50 a program for performingpixel density conversion on image data expressing radiographic imagesdetected by the radiation detector 42 is stored on the ROM 62 and/or theHDD 66. The image data output to the display device 80 is accordinglyimage data after performing pixel density conversion.

FIG. 5 is a flow chart showing an example of an imaging processingsequence executed in the image processing apparatus 50 of a radiographicimaging system 100 according to the present exemplary embodiment. Atstep S100 of FIG. 5, the amount of radiation irradiated from theradiation irradiation section 24 is detected in the radiation detector42 of the imaging apparatus 41. Then at step S102 determination is madeas to whether or not the radiation amount has exceeded a predeterminedthreshold value. When determined that the amount of radiation irradiatedhas exceeded the threshold value, it is determined that sufficientsensitively can be obtained for imaging (image S/N will be sufficient).Processing then proceeds to step S104, ON signals are output in sequenceone line at a time to the first scan lines G1-0 to G1-7, scan signalsare transmitting to the respective plural pixels 20, and normalprocessing to read the charge signals accumulated in the storagecapacitors 5 of each of the pixels 20 is performed (still imaging mode).

However, when determined at step S102 that the amount of radiationirradiated is the threshold value or lower, it is considered that theS/N for the image obtained would be insufficient, processing proceeds tostep S106, and processing is performed to image a high S/N image.Specifically, the pixel groups A, B, C, D, E etc. formed from specific 4pixels are set as described above. At step S108, scan signals (ONsignals) are output by the scan signal control section 35 to the secondscan lines G2 and the third scan lines G3 to switch on the TFT switches4 b of each of the pixels disposed in the pixel groups A, B, C, D, Eetc., and binning processing is performed to treat the 4 pixels of eachof the pixel groups as a single pixel. Thus, if the amount of radiationirradiated is the threshold value or lower, a radiographic image withgood S/N is obtained by processing to combine the charges of pluralpixels (binning) due to the consideration that otherwise there would beinsufficient imaging sensitivity.

Note that, in the imaging process shown in FIG. 5, process is performedin consideration of the S/N of the radiographic image that will beobtained according to the amount of radiation irradiated. However thereis no limitation thereto. For example, configuration may be made so asto switch between normal processing without binning and processing withbinning according to instruction for the still imaging mode or the videoimaging mode, irrespective of the amount of radiation irradiated.Configuration may be made to perform the above switching according tothe required resolution for imaging.

Thus, in the present exemplary embodiment, in the radiation detectionelement 10 of the radiation detector 42, scan lines G1 are disposed foreach pixel row connected to the TFT switches 4 a in each of the pixels20 of plural pixels 20 having hexagonal shaped pixel regions arrayed ina honeycomb pattern, and for the predetermined plural pixel groups eachconfigured from 4 pixels, scan lines G2 and G3 are disposed for eachpixel row for performing binning processing by reading and combining 4pixels worth of charges at the same timing. The binning processing scanlines G2 and G3 then output a signal to simultaneously switch ON the TFTswitches 4 b in the pixels of specific plural pixel groups, andconfiguration is made such that the charge signals for the combinedcharges of each of the respective plural pixel groups flow in theseparate respective data lines.

By so doing, when binning processing performed by simultaneously readingand combining 4 pixels worth of charges for the plural pixel groups,imaging may be performed at 4 times the rate in comparison to whenreading the charge signals from the individual pixels without binningprocessing. Accordingly, in the present exemplary embodiment, the S/Nmay be raised by increasing the amount of charge collected, may enableapplication to a video imaging mode demanding a high frame rate as wellas application to low sensitivity images generated by irradiating asmall amount of radiation.

Namely, when performing video imaging, the pixel groups configured from4 pixels are treated as a single pixel, the charges are simultaneouslyread from plural pixel groups, and binning process is performed tocombine the charges accumulated in each of the pixels configuring thesepixel groups. Hence, although the resolution is lower than for a stillimage, a frame rate that is 4 times (a frame duration of ¼) that of thestill imaging mode can be achieved for reading charges successively fromeach pixel row.

Moreover, combination of 4 pixels in each of the pixel groups isdetermined such that plural hexagonal shaped regions are arrayed in ahoneycomb pattern. Each of the plural hexagonal shaped regions areformed by including inside 1 center of gravity of the region surroundedby the outlines of the pixel groups and the line segments connecting the6 individual centers of gravity present at the periphery of the 1 centerof gravity. Accordingly, unevenness of the pixel positions (the centerof gravity position when plural pixels are treated a single pixel clump)after binning in each of the horizontal, vertical and diagonaldirections may be suppressed, and even resolution may be secured in eachof the respective directions, similarly to in an image before binning.As a result, a common integrated circuit (IC) may be employed for pixeldensity conversion before and after binning. Further, processing can beperformed employing the same algorithm even in processing byprogrammable devices such as a FPGA and software rather than with an ICwith fixed circuit.

Second Exemplary Embodiment

Explanation follows regarding a radiographic imaging system 100according to a second exemplary embodiment of the present invention.Note that the radiographic imaging system 100 according to the secondexemplary embodiment is similar to the radiographic imaging system 100according to the first exemplary embodiment illustrated in FIG. 1, andso illustration and further explanation will be omitted.

FIG. 6 illustrates an electrical configuration of a radiation detector142 in an imaging apparatus 41 of a radiographic imaging system 100according to the present exemplary embodiment. A radiation detectionelement 110 of a radiation detector 142 illustrated in FIG. 6 isconfigured with plural pixels 20 that have hexagonal shaped pixelregions arrayed adjacently in a two dimensional honeycomb pattern, suchthat the pixels 20 arrayed in a honeycomb pattern configure arectangular shaped pixel region. Each of the pixels 20 is configuredsimilarly to in the radiation detection element 10 of the radiationdetector 42 illustrated in FIG. 2.

The radiation detector 142 includes: fourth scan lines G4-1 to G4-4(also referred to as fourth scan lines G4) connected to the gateelectrodes of the TFT switches 4 a provided in each of the pixels 20 forON/OFF controlling the TFT switches 4 a; fifth scan lines G5-1, G5-2(also referred to as fifth scan lines G5) connected to the gateelectrodes of the TFT switches 4 b for ON/OFF controlling the TFTswitches 4 b, plural data lines D1 to D3 (also referred to as data linesD) that read charges generated in sensor portions 103 and accumulated incharge storage capacitors 5; and common ground lines 30.

In FIG. 6, for ease of explanation and illustration, an example is shownof a configuration laid out with 4 lines of the fourth scan lines G4, 2lines of the fifth scan lines G5, 3 lines of the data lines D, and 3lines of the common ground lines 30. When, for example, there are m×nindividual pixels 20 respectively disposed in the row direction and thecolumn direction (wherein m and n are positive integers), there are mlines of the fourth scan lines G4 and n lines of the data lines Dprovided. In such cases, the number of the fifth scan lines G5 is halfthe number of the fourth scan lines G4, namely m/2 lines are provided.The radiation detection element 110 of the radiation detector 142employs a radiation—charge conversion material such as amorphousselenium, as described later, in a configuration that directly convertsradiation to charges. Note that, the common lines (not shown in thedrawings) are connected to the sensor portions 103 of each of the pixels20, in a configuration in which a bias voltage from a power source (notshown in the drawings) is applied through the common lines.

In the radiation detector 142, the scan lines G4, G5 are disposed so asto intersect with the data lines D and the common ground lines 30. Thedata lines D are laid out along the peripheral edges of the pixels 20with hexagonal shaped pixel regions in a zigzag pattern (so as tomeander) so as to bypass these pixels 20. Namely, the data lines Dextend in the column direction while running along 3 adjoining sides outof the peripheral edges (6 sides) of each of the individual pixels 20.The common ground lines 30 are also disposed in a zigzag pattern (so asto meaner) so as to keep away from the TFT switches 4 a, 4 b of each ofthe pixels 20.

The gate electrodes of the TFT switches 4 a are connected to the fourthscan lines G4, and the gate electrodes of the TFT switches 4 b areconnected to the fifth scan lines G5. One or other of the drainelectrodes or the source electrodes of the TFT switches 4 a, 4 b areconnected to one electrode of the charge storage capacitors 5, and theother of the drain electrodes or the source electrodes are connected tothe data lines D. When imaging a radiographic image with the radiationdetector 142, during irradiation with external radiation (X-rays), OFFsignals are output to the fourth scan lines G4 and each of the TFTswitches 4 a is switched OFF, and OFF signals are output to the fifthscan lines G5, switching each of the TFT switches 4 b OFF. Accordingly,the charges generated in a semiconductor layer are accumulated in eachof the charge storage capacitors 5.

When reading an image, for example a still image, ON signals are outputin sequence one line at a time to the fourth scan lines G4, switchingthe TFT switches 4 a in each of the pixels 200N. Or, for example whenreading a video image, ON signals are output in sequence one line at atime to the fifth scan lines G5, switching ON the TFT switches 4 b ofplural pixels in pixel groups. The charges accumulated in each of thecharge storage capacitors 5 are thereby read as electrical signals, anda radiographic image is obtained by converting the read electricalsignals into digital data.

A signal processing section 125 includes signal detectors (not shown inthe drawings) that detect charges flowing out of each of the data linesD1 to D3 as electrical signals, and subjects the detected electricalsignals to specific processing. The signal processing section 125 alsooutputs control signals expressing a signal detection timing and controlsignals expressing a scan signal output timing respectively to each ofthe signal detectors and scan signal control sections 35 a, 35 b. As aresult, on receipt of the control signals from the signal processingsection 125, the scan signal control section 35 a outputs scan signalsto the fourth scan lines G4-1 to G4-4 for switching the TFT switches 4 aON/OFF. The scan signal control section 35 b also outputs scan signalsto the fifth scan lines G5-1, G5-2 for switching the TFT switches 4 bON/OFF.

The charge signals transmitted by the individual data lines D1 to D3 areamplified in the signal processing section 125 by amplifiers and held insample-and-hold circuits, not shown in the drawings. The charge signalsheld by the individual sample-and-hold circuits are input in sequence toa multiplexer (not shown in the drawings), and then converted intodigital image data by an A/D converter. Note that the digital image dataoutput from the A/D converter is, for example, stored in sequence in theimage memory 90 as digital image data for plural frames worth of imagedradiographic images.

Explanation next follows regarding operation of the radiation detector142 according to the present exemplary embodiment. During imagedetection with the radiation detector 142, OFF signals (for example, 0V)are output from the scan signal control sections 35 a, 35 b to thefourth scan lines G4-1 to G4-4 and the fifth scan lines G5-1, G5-2,applying a negative bias to the gate electrodes of the TFT switches 4 a,4 b. Each of the TFT switches 4 a, 4 b are thereby maintained in an OFFstate.

During image reading, the radiation detector 142 performs in a stillimaging mode or a video imaging mode, according to instruction from animage processing apparatus. When instruction was for the still imagingmode, the signal processing section 125 controls the scan signal controlsections 35 b such that scan signals are output from the fifth scanlines G5-1, G5-2 for switching OFF the TFT switches 4 b in each of thepixels 20. The signal processing section 125 also controls the scansignal control sections 35 a to apply ON signals for example with avoltage of +10 V to 20 V in sequence from the fourth scan lines G4-1 toG4-4 to the gates of each of the TFT switches 4 a, in order to switch ONthe TFT switches 4 a in each of the pixels 20. The TFT switches 4 a ineach of the pixels 20 are thereby switched to an ON state in sequencefor each of the pixel rows, charges are read from the sensor portions103 by the TFT switches 4 a, and signals corresponding to these chargesare output to the data lines D.

Thus in the radiation detector 142, in the still imaging mode, in eachof the data lines D1 to D3 charge signals flow corresponding to each ofthe pixels 20 in each of the pixel rows. Image data expressing an imagerepresenting radiation irradiated onto the radiation detection element110 of the radiation detector 142 can accordingly be obtained. In thesignal processing section 125, the charge signals are then convertedinto digital signals, and a radiographic image based on the image datacorresponding to the charge signals is generated.

Explanation follows regarding the video imaging mode. In the radiationdetector 142 according to the present exemplary embodiment, out of theplural pixels 20 illustrated in FIG. 6, for example, the gate electrodesof each of the TFT switches 4 b in the 4 pixels P2, P3, P5, P6surrounded by a dashed line are connected to the fifth scan line G5-1.Similarly, the gate electrodes of each of the TFT switches 4 b in the 4pixels P8, P9, P11, P12 surrounded by a dashed line are connected to thefifth scan line G5-2. The pixels P2, P3, P5, P6 are referred to togetheras pixel group PG1, and the pixels P8, P9, P11, P12 are referred totogether as pixel group PG2. Note that the pixel groups in the radiationdetection element 110, while omitted from illustration in FIG. 6, arealso configured by plural other pixel groups each formed from 4 specificpixels other than the pixel groups PG1, PG2 (see for example FIG. 7).

When the video imaging mode is instructed to the radiation detector 142,the signal processing section 125 controls the scan signal controlsection 35 a so as to switch OFF the TFT switches 4 a of each of thepixels 20, and outputs OFF signals from the fourth scan lines G4-1 toG4-4 to each of the gate electrodes of the TFT switches 4 a of each ofthe pixels 20.

The signal processing section 125 also controls the scan signal controlsection 35 b to sequentially drive the fifth scan lines G5-1, G5-2 tooutput scan signals (ON signals). Namely, the TFT switches 4 b of thefour individual pixels P2, P3, P5, P6 of pixel group PG1 are switched ONwhen the ON signal is output from the fifth scan line G5-1. As a resulta combined charge signal summing the charges accumulated in each of thecharge storage capacitors 5 of the four individual pixels P2, P3, P5, P6is output to the data line D2. Then, the TFT switches 4 b of the fourindividual pixels P8, P9, P11, P12 of pixel group PG2 are switched ONwhen the ON signal is output from the fifth scan line G5-2. In this casea combined charge signal summing the charges accumulated in the fourindividual pixels P8, P9, P11, P12 is output to the data line D1.

While omitted from illustration in FIG. 6, when the ON signals areoutput by the fifth scan lines G5-1, G5-2, in the other plural pixelsfollowing in the row direction from the pixels of the pixel groups PG1,PG2, charge signals summed in 4 pixel units are also output to datalines similarly to with the pixel groups PG1, PG2.

Thus, when in the video imaging mode, in each of the plural pixel groupsconfigured by four pre-specified pixels that have been bundled togetherfrom the plural pixels 20 configuring the radiation detection element110, the charges accumulated in the four individual pixels are combined(binned), and a combined charge signal corresponding to the binnedcharges is output to the respective data lines. This means that whenperforming video imaging, charge signals corresponding to the sum of 2pixels×2 pixels flow alternately in adjacent data lines D (in FIG. 6alternately in the even numbered data lines D2 and the odd numbered datalines D1 and D3).

FIG. 7 illustrates a layout of pixels and pixel groups subject tobinning in the video imaging mode described above. Note that in FIG. 7the shading pattern is changed in each of the pixels in adjacent pixelgroups to make it easier to discriminate the respective pixel groupsfrom each other.

In the example illustrated in FIG. 7, the radiation detection element110 of the radiation detector 142 specifies pixel groups A, B, C, D, E,F, G, H formed from 4 adjacent pixels as described above. For example,the pixel group A is configured from a total of 4 pixels (the 4 pixelsapplied with a vertical line pattern), these being 2 adjacent pixels outof the pixels 20 in a first pixel row that is along the row directionappended with 20 a in FIGS. 7, and 2 mutually adjacent pixels out of thepixels 20 in a second pixel row positioned in the row below the firstpixel row along the row direction appended with 20 b in FIG. 7,displaced by ½ the array pitch of the first pixel row to the first 2pixels.

Each of the pixel groups can be defined as being a combination of 4pixels configured by 3 pixels disposed such that two adjoining sides ofeach of the pixels are respectively mutually adjacent to one side of theremaining 2 pixels, and by 1 pixel disposed such that two adjoiningsides are respectively mutually adjacent to one side of 2 pixels out ofthe 3 pixels. The combination of 4 pixels may also be described as beinga combination of 4 pixels formed from 2 pairs of mutually adjacentpixels disposed alongside each other, with 2 adjoining sides of 1 pixelfrom a first pair respectively disposed mutually adjacent to 1 side ofeach of the 2 pixels in the other pair.

When still imaging mode is instructed, as described above, in theradiation detector 142, the signal processing section 125 switches ONthe TFT switches 4 a in each of the pixels 20 of the radiation detector142, reads the charges from each of the pixels, and outputs signalscorresponding to the charges to the data lines D. Since pixels withhexagonal shaped pixel regions are employed as the individual pixels inthe radiation detection element 110 of the radiation detector 142 a highresolution may be secured in each of the horizontal, vertical anddiagonal directions.

However, in the video imaging mode, due to the signal processing section125 switching ON the TFT switches 4 b in the respective 4 pixelsconfiguring each of the pixel groups, the 4 pixels act as a singlepixel, and binning is performed to combine 4 pixels worth of charges.The positions of the center of gravity for each of the pixel groups A,B, C, D, E, F, G, H formed from 4 pixels are positioned at the blackdots indicated respectively as a, b, c, d, e, f, g, h.

In the example indicated in FIG. 7, when performing 4 pixel binning foreach of the pixel groups, a regular hexagonal shape is formed byconnecting the centers of gravity a-c-g-h-e-b-a, with the center ofgravity d of the pixel group D at the center. It can also be seen thatthe inter-center of gravity distances of these pixel groups, namely inthe 6 directions d to a, d to c, d to g, d to h, d to e, d to b, are allthe same as each other. Thus, in the present exemplary embodiment, bymaking the pixel regions of each of the pixels 20 a hexagonal shape,even resolution may be secured in each of the horizontal, vertical anddiagonal directions before binning. Moreover, in the present exemplaryembodiment, since a regular hexagonal shape is also formed by connectingtogether the centers of gravity of the pixel groups, even resolution mayalso be secured in each of the horizontal, vertical and diagonaldirections after binning.

Namely, the combinations of each of the pixels in each of the pixelgroups are determined such that plural hexagonal shaped regions arearrayed in a honeycomb pattern. By employing, for example, the centersof gravity a, b, c, d, e, g, h of each of the regions surrounded by theoutlines of the pixel groups A, B, C, D, E, F, G, H, each of thehexagonal shaped regions are formed including, 1 center of gravity d atthe inside, and hexagonal shaped regions formed by the line segmentsconnecting the 6 individual centers of gravity a, c, g, h, e, b presentat the periphery of the center of gravity d. Accordingly, the presentexemplary embodiment may suppress unevenness in each of the horizontal,vertical and diagonal directions of the pixel positions (the center ofgravity positions of the pixel groups) after binning, and may enableeven resolution to be secured in each of the respective directions,similarly to in an image before binning.

Since the centers of gravity arrayed before binning, and the centers ofgravity arrayed after binning, both are in a state in which hexagonalshaped regions formed by the centers of gravity are arrayed in ahoneycomb pattern, processing may be performed with a similar algorithmwhen performing pixel density conversion after binning and to whenperforming pixel density conversion without binning Namely, thealgorithm for pixel density conversion processing may be commonlyemployed both before and after binning, without preparing anotherseparate algorithm for pixel density conversion processing afterbinning.

Note that, since the imaging processing executed in the imagingapparatus 41 of the radiographic imaging system 100 according to thepresent exemplary embodiment is similar to the imaging processingexecuted by the imaging apparatus 41 according to the first exemplaryembodiment illustrated in FIG. 5, further explanation thereof isomitted.

Thus, as explained above, in the present exemplary embodiment, for eachof the respective predetermined plural pixel groups each configured from4 pixels out of the plural pixels with hexagonal shaped pixel regionsarrayed in a honeycomb pattern in the radiation detector, binningprocess is performed by simultaneously reading and combining 4 pixelsworth of charges, in the radiation detection element 110 of theradiation detector 142. Accordingly, in the present exemplaryembodiment, the S/N may be raised by increasing the amount of chargecollected, and may enabling application to a video imaging modedemanding a high frame rate as well as application to low sensitivityimages generated by irradiating a small amount of radiation.

Moreover, combination of each of the pixels in each of the pixel groupsis determined such that plural hexagonal shaped regions are arrayed in ahoneycomb pattern. Each of the plural hexagonal shaped regions areformed by including inside 1 center of gravity of the region surroundedby the outlines of the pixel groups and the line segments connecting the6 individual centers of gravity present at the periphery of the 1 centerof gravity. Accordingly, unevenness of the pixel positions (the centerof gravity position when plural pixels are treated a single pixel clump)after binning in each of the horizontal, vertical and diagonaldirections may be suppressed, and even resolution may be secured in eachof the respective directions, similarly to in an image before binning.As a result, a common integrated circuit (IC) may be employed for pixeldensity conversion before and after binning.

Moreover, when performing video imaging, the pixel groups configuredfrom 2 pixels×2 pixels are read as a single pixel; and binning processis performed combining the charges accumulated in each of the pixelsconfiguring each of the pixel groups. Hence, although the resolution islower than for a still image, a frame rate can be achieved that is 2times (a frame duration of ½) that for reading charges from each pixelrow in the still imaging mode.

Moreover, by thus providing the scan lines G5 for binning, one for eachadjacent pair of the pixel rows in the plural pixel rows, the number ofscan lines G can be reduced to ½ the number of pixel rows subject tobinning, in comparison to cases in which scan lines G are provided onefor each of the pixel rows subject to binning. Namely, the number ofscan lines G can be greatly reduced in comparison to the radiationdetector 42 according to the first exemplary embodiment illustrated inFIG. 2. Moreover, in the configuration of the radiation detector 142illustrated in FIG. 6, in comparison to the 4 scan lines G1 requiredwhen binning is not performed, the total number of scan lines requiredfor scanning the pixels, including performing scanning with binning, haspreviously been twice the 4 lines, i.e. 8 lines. However, in the presentexemplary embodiment only 1.5 times the 4 lines, i.e. 6 lines, arerequired.

Third Exemplary Embodiment

Explanation next follows regarding a radiographic imaging system 100according to a third exemplary embodiment of the present invention. Notethat the radiographic imaging system 100 according to the thirdexemplary embodiment is similar to the radiographic imaging system 100according to the first exemplary embodiment illustrated in FIG. 1, andso illustration and further explanation will be omitted.

FIG. 8 illustrates an electrical configuration of a radiation detector342 in an imaging apparatus 41 according to the third exemplaryembodiment. A radiation detection element 310 of a radiation detector342 illustrated in FIG. 8 is, similarly to the radiation detector 42according to the first exemplary embodiment illustrated in FIG. 2,configured with plural pixels 20 that have hexagonal shaped pixelregions arrayed adjacently in a two dimensional honeycomb pattern, suchthat the pixels 20 arrayed in a honeycomb pattern configure arectangular shaped pixel region.

The radiation detector 342 includes plural scan lines G6-0 to G6-12,G7-0 to G7-11 arrayed parallel to a row direction (the horizontaldirection in FIG. 8) and plural data lines D1 to D6 that intersect thescan lines and are provided extending along a column direction (thevertical direction in FIG. 8) bending around the periphery of the pixels20. For simplicity the scan lines G6-0 to G6-12 are referred to below assixth scan lines G6 and the scan lines G7-0 to G7-11 are referred to asseventh scan lines G7.

Similarly to in the radiation detector 42 according to the firstexemplary embodiment, common ground lines 30 are disposed intersectingwith the scan lines G6 and G7 as straight lines between the plural datalines D1 to D6 and without intersecting with the data lines D1 to D6.

Note that, disposing the common ground lines 30 as straight lines meansthat a straight state is maintained within a range obtainable whileallowing for manufacturing error in manufacturing processes of theradiation detection element 310.

Each of the pixels 20 in the radiation detection element 310 isconfigured including a sensor portion 103 that receives radiation(X-rays) that has been irradiated and generates charges, a chargestorage capacitor 5 that accumulates the charges that have beengenerated in the sensor portion 103, and two TFT switches 4 a, 4 b forreading the charges accumulated in the charge storage capacitors 5. Theradiation detector 342 is accordingly a direct-conversion-type radiationdetector 342 that employs a radiation—charge conversion material, suchas amorphous selenium, in a photoelectric conversion layer to absorbradiation and convert it into charges.

Explanation follows regarding operation when imaging a radiographicimage with the radiation detector 342 according to the third exemplaryembodiment. For example, in a still imaging mode, scan signals areoutput from a scan signal control section 335 to the sixth scan linesG6-0 to G6-12 so as to switch ON the TFT switches 4 a in each of thepixels 20 in sequence by pixel row, and scan signals are output from thescan signal control section 335 to the seventh scan lines G7-0 to G7-11to switch OFF the TFT switches 4 b in each of the pixels 20.Accordingly, the charges are read out from the sensor portions 103 ineach of the pixels, and signals corresponding to these charges areoutput to the data lines D1 to D6. Image data expressing imagesrepresenting radiation that has been irradiated onto the radiationdetector 342 is thereby obtained from the charge signals correspondingto each of the pixels 20.

When in video imaging mode, scan signals are output from the scan signalcontrol section 335 to the sixth scan lines G6-0 to G6-12 to switch OFFthe TFT switches 4 a in each of the pixels 20, and scan signals areoutput to the seventh scan lines G7-0 to G7-11 to switch ON the TFTswitches 4 b in each of the pixels 20 as described below.

The radiation detection element 310 of the radiation detector 342according to the present exemplary embodiment is configured with pluralpixel groups respectively configured from 3 predetermined pixels. Forexample, as shown in FIG. 8, the 3 pixels P0 to P2 form a pixel groupPG0, the 3 pixels P3 to P5 form a pixel group PG1, the 3 pixels P6 to P8form a pixel group PG2, the 3 pixels P9 to P11 form a pixel group PG3,the 3 pixels P12 to P14 form a pixel group PG4, the 3 pixels P15 to P17form a pixel group PG5, the 3 pixels P18 to P20 form a pixel group PG6,and the 3 pixels P21 to P23 form a pixel group PG7.

Out of the seventh scan lines, the scan line G7-0 is connected to thegate electrodes of each of the TFT switches 4 b in the pixels P0 to P2configuring the pixel group PG0 and the gate electrodes of each of theTFT switches 4 b in the pixels P3 to P5 of pixel group PG1. Out of theseventh scan lines, the scan line G7-1 is connected to the gateelectrodes of each of the TFT switches 4 b in the pixels P6 to P8configuring the pixel group PG2 and the gate electrodes of each of theTFT switches 4 b in the pixels P9 to P11 of pixel group PG3. The scanline G7-0 and the scan line G7-1 are configured as branches of a signalline extending form the scan signal control section 335.

Hence, when a scan signal (ON signal) is output by the scan signalcontrol section 335 to the scan lines G7-0, G7-1, the TFT switches 4 bof all of the pixels 20 in the pixel groups PG0 to PG3 are switched ON.As a result the charges accumulated in each of the charge storagecapacitors 5 of the 3 individual pixels configuring the respective pixelgroups PG0 to PG3 are combined (binned), and the combined charge signalof the pixel group PG0 is output to the data line D1, the combinedcharge signal of the pixel group PG1 is output to the data line D4, thecombined charge signal of the pixel group PG2 is output to the data lineD3, and the combined charge signal of the pixel group PG3 is output tothe data line D6.

Connections between the each of the TFT switches 4 b in each of thepixels configuring the pixel groups PG4 to PG7 and the scan lines G7-2,G7-3 are made in a similar pattern to the connections between the pixelgroups PG0 to PG3 and the scan lines G7-0, G7-1 described above.Accordingly, when scan signals (ON signals) are output by the scansignal control section 335 to the scan lines G7-2, G7-3 the TFT switches4 b of all of the pixels 20 in the pixel groups PG4 to PG7 are switchedON. As a result, a combined charge signal (binned signal) of the pixelgroup PG4 is output to the data line D1, a combined charge signal ofpixel group PG5 is output to the data line D4, a combined charge signalof the pixel group PG6 is output to the data line D3, and a combinedcharge signal of the pixel group PG7 is output to the data line D6.

The above similarly applies to other pixel groups. Specifically, forexample, the pixel groups PG8 to PG11 receive scan signals from the scanlines G7-4, G7-5, the pixel groups PG12 to PG15 receive scan signalsfrom the scan lines G7-6, G7-7, the pixel groups PG16 to PG19 receivescan signals from the scan lines G7-8, G7-9, and the pixel groups PG20to PG23 receive scan signals from the scan lines G7-10, G7-11.

Thus, in the radiation detector 342, when the pixel groups PG0 to PG3,PG8 to PG11, PG16 to PG19 are referred to as even numbered blocks, andwhen the pixel groups PG4 to PG7, PG12 to PG15, PG20 to PG23 arereferred to as odd numbered blocks, charge signals of charges summed in3-pixel units in the radiation detector 342, alternately for evennumbered blocks and odd numbered blocks, flow out into the data linesD1, D3, D4, D6. Charge signals do not flow in the data lines D2, D5during binning and are in a floating state.

As described above, the binning scan lines G7 are split into pluralgroups, and scan signals for TFT switches 4 b are sent to the scan linesG7 belonging to these groups with timings shifted for each of thegroups. Thereby, when combining and reading charges for the plural pixelgroups with each timing, charge signals corresponding to combined chargeamounts read out from different pixel groups are not transmitted throughthe same data line.

Note that, for the data lines D2, D5 that are in a floating state duringbinning process, configuration may be made such that a floating state isavoided by, for example, connecting the source electrodes or the drainelectrodes of the TFT switches 4 b to the data lines D2, D5 fixed at aspecific electrical potential, or connected to lines in the vicinity.

Moreover, whilst in FIG. 8 the scan lines G7-0 to G7-1, G7-2 to G7-3etc. are configured as 2 branches from a single line respectivelyextending from the scan signal control section 335. However, there is nolimitation thereto. For example, the scan lines G7-0 to G7-1 may beextended separately from the scan signal control section 335 and may bedriven simultaneously, and then the scan lines G7-2 to G7-3 may bedriven simultaneously. Configuration may also be made with a second scansignal control section provided separately to the scan signal controlsection 335 in which 1 line extending out from the second scan signalcontrol section branches into 2. Configuration may also be made suchthat the scan lines G7-0 to G7-3 are extended separately out from thesecond scan signal control section that is separate to the scan signalcontrol section 335, and the scan lines G7-0, G7-1 are drivensimultaneously, and then the scan lines G7-2, G7-3 are drivensimultaneously.

In the example illustrated in FIG. 8, for ease of explanation andillustration, an example is shown of a configuration laid out with 25scan lines G and 6 data lines D. When, for example, there are m×nindividual pixels 20 disposed in the row direction and the columndirection (wherein m and n are positive integers), 2 m scan lines and ndata lines D are provided.

FIG. 9 illustrates a layout of pixels and pixel groups subject tobinning in the video imaging mode, described above. The shading patternis again changed for each of the pixels in adjacent pixel groups to makeit easier to discriminate the respective pixel groups from each other.In the example illustrated in FIG. 9, the radiation detection element310 of the radiation detector 342 specifies pixel groups A, B, C, D, E,F, G each formed from adjacent 3 pixels as described above. Each of thepixel groups here is configured by 3 pixels, these being a first pixelout of the plural pixels and 2 other pixels, a second pixel and a thirdpixel, adjacent to each other in a row adjacent to the first pixel row.The three individual pixels are disposed such that two adjoining sidesof the first pixel are respectively adjacent to one side of each of thesecond pixel and the third pixel. Namely, each of the pixel groups canbe defined as being a combination of 3 pixels, made up from 3 pixelsdisposed such that two adjoining sides of each of the pixels arerespectively adjacent to one side of each of the other 2 pixels.

In the radiation detector 342 of the present exemplary embodiment, whenthe still imaging mode is instructed as described above, the signalprocessing section 325 switches ON the TFT switches 4 a in each of thepixels 20 of the radiation detector 342, reads the charges from each ofthe pixels, and outputs signals corresponding to the charges to the datalines D. Since pixels with hexagonal shaped pixel regions are employedas the individual pixels in the radiation detection element 310 of theradiation detector 342 a high resolution can be secured in each of thehorizontal, vertical and diagonal directions. However, in the videoimaging mode, due to the signal processing section 325 switching ON theTFT switches 4 b in the respective 3 pixels configuring each of thepixel groups, the 3 pixels act as a single pixel, and binning isperformed to combine 3 pixels worth of charges.

In FIG. 9, the positions of the center of gravity for each of the pixelgroups A, B, C, D, E, F, G formed from 3 pixels are positioned at theblack dots indicated respectively as a, b, c, d, e, f, g. In the exampleindicated in FIG. 9, when performing 3 pixel binning for each of thepixel groups, a regular hexagonal shape is formed with the center ofgravity d of the pixel group D at the center by connecting the centersof gravity a-b-c-e-f-a of the other pixel groups. It can also be seenthat the inter center of gravity distances of these pixel groups, namelyin the 6 directions d to a, d to b, d to c, d to e, d to f, d to g, areall the same as each other. Thus by making the pixel regions of each ofthe pixels 20 a hexagonal shape, even resolution may be secured in eachof the horizontal, vertical and diagonal directions before binning.Moreover, since a regular hexagonal shape is also formed by connectingtogether the centers of gravity of the pixel groups, even resolution mayalso be secured in each of the horizontal, vertical and diagonaldirections after binning.

Namely, the combinations of each of the pixels in each of the pixelgroups are determined such that plural hexagonal shaped regions arearrayed in a honeycomb pattern. By employing, for example, the center ofgravity a, b, c, d, e, f, g of each of the regions surrounded by theoutlines of the pixel groups A, B, C, D, E, F, G, each of the hexagonalshaped regions are formed including, 1 center of gravity d at theinside, and hexagonal shaped region formed by the line segmentsconnecting the 6 individual centers of gravity a, b, e, g, f, c presentat the periphery of the center of gravity d. Accordingly, the presentexemplary embodiment may suppress unevenness in each of the horizontal,vertical and diagonal directions of the pixel positions (the center ofgravity positions of the pixel groups) after binning, and may enableeven resolution to be secured in each of the respective directions,similarly to in an image before binning.

In the present exemplary embodiment, similarly to in the first exemplaryembodiment described above, since the centers of gravity arrayed beforebinning, and the centers of gravity arrayed after binning, both are in astate in which hexagonal shaped regions formed by the centers of gravityare arrayed in a honeycomb pattern, processing may be performed with asimilar algorithm when performing pixel density conversion after binningto when performing pixel density conversion without binning. Hence, thealgorithm for pixel density conversion processing may be commonlyemployed both before and after binning, without preparing anotherseparate algorithm for pixel density conversion processing afterbinning.

As described above, in the third exemplary embodiment, in the radiationdetection element 310 of the radiation detector 342, scan lines G7 aredisposed for each pixel row in order to perform binning processing toread and combine respective 3 pixels worth of charges for predeterminedplural pixel groups each configured from 3 pixels, and signals areoutput to specific binning processing scan lines G7 to simultaneouslyswitch ON the TFT switches 4 b in each of the pixels of plural pixelgroups. Then, configuration is made such that charge scan signals forthe charges combined in each of the plural pixel groups flow in separatedata lines.

Due to the above configuration, the present exemplary embodiment maysimultaneously read and combine 3 pixels worth of charges for the pluralpixel groups during binning process, imaging may be performed at 2 timesthe rate in comparison to when reading out the charge signals from theindividual pixels 20 without binning. As a result, the present exemplaryembodiment may raise the S/N by increasing the amount of chargecollected, enable application to a video imaging mode demanding a highframe rate as well as enabling application to low sensitivity imagesgenerated by irradiating a small amount of radiation.

Namely, when performing video imaging, the pixel groups configured from3 pixels are treated as a single pixel, the charges are simultaneouslyread from plural pixel groups, and binning processing is performed tocombine the charges accumulated in each of the pixels configuring thesepixel groups. Hence, although the resolution is lower than for a stillimage, a frame rate of 2 times (a frame duration of ½) that of the stillimaging mode for reading charges sequentially from each pixel row may beachieved.

Fourth Exemplary Embodiment

Explanation follows regarding a radiographic imaging system 100according to a fourth exemplary embodiment of the present invention.Note that the radiographic imaging system 100 according to the fourthexemplary embodiment is configured similarly to the radiographic imagingsystem 100 according to the first exemplary embodiment described above,and so illustration and further explanation will be omitted.

FIG. 10 illustrates an electrical configuration of a radiation detector442 in an imaging apparatus of a radiographic imaging system 100according to the fourth exemplary embodiment. A radiation detectionelement 410 of a radiation detector 442 illustrated in FIG. 10 is,similarly to the radiation detector 42 according to the first exemplaryembodiment illustrated in FIG. 2, configured with plural pixels 20 thathave hexagonal shaped pixel regions arrayed adjacently in a twodimensional honeycomb pattern, configuring a region that is rectangularshaped overall.

The radiation detector 442 includes: eighth scan lines G8-1 to G8-5(also referred to as eighth scan lines G8) connected to the gateelectrodes of the TFT switches 4 a provided in each of the pixels 20 forON/OFF controlling the TFT switches 4 a; ninth scan lines G9-1, G9-2(also referred to as ninth scan lines G9) connected to the gateelectrodes of TFT switches 4 b for ON/OFF controlling the TFT switches 4b; plural data lines D1 to D3 (also referred to as data lines D) thatread charges generated in sensor portions 103 and accumulated in chargestorage capacitors 5; and common ground lines 30.

Note that out of the plural pixels 20, for example pixels P6, P12 and soon each only have the TFT switch 4 a as a transistor for reading chargesaccumulated in the charge storage capacitor 5 in each of the pixels dueto the relationship to the timing for reading charges in an imagingmode.

In FIG. 10, for ease of explanation and illustration, an example isshown of a configuration laid out with 5 lines of the eighth scan linesG8, 2 lines of the ninth scan lines G9, 4 lines of the data lines D, and4 lines of the common ground lines 30. In general when, for example,there are m×n individual pixels 20 respectively disposed in the rowdirection and the column direction (wherein m and n are positiveintegers), there are m lines of the eighth scan lines G8 and n datalines provided. The radiation detection element 410 of the radiationdetector 442 employs a radiation—charge conversion material such asamorphous selenium that directly converts radiation to charges. Notethat the common lines (not shown in the drawings) are connected to thesensor portions 103 of each of the pixels 20 in which a bias voltagefrom a power source (not shown in the drawings) is applied through thecommon lines.

In the radiation detector 442, the scan lines G8, G9 are disposed so asto intersect with the data lines D and the common ground lines 30. Thedata lines D are laid out along the peripheral edges of the pixels 20with hexagonal shaped pixel regions in a zigzag pattern (so as tomeander) so as to bypass these pixels 20. Namely, the data lines Dextend in the column direction while running along 3 adjoining sides ofthe peripheral edges (6 sides) of each of the pixels 20. The commonground lines 30 are also disposed in a zigzag pattern (so as to meaner)so as to keep away from the TFT switches 4 a, 4 b of each of the pixels20.

The gate electrodes of the TFT switches 4 a are connected to the eighthscan lines G8, and the gate electrodes of the TFT switches 4 b areconnected to the ninth scan lines G9. One or other of the drainelectrodes or the source electrodes of the TFT switches 4 a, 4 b areconnected to one electrode of the charge storage capacitors 5, and theother of the drain electrodes or the source electrodes are connected tothe data lines D.

A control section 150 of the radiation detector 442 outputs controlsignals expressing signal detection timing, and control signalsexpressing scan signal output timing to scan signal control sections 435a, 435 b. On receipt of the control signals from the control section150, the scan signal control section 435 a outputs scan signals to theeighth scan lines G8-1 to G8-5 for switching the TFT switches 4 aON/OFF. The scan signal control section 435 b also outputs scan signalsto the ninth scan lines G9-1, G9-2 for switching the TFT switches 4 bON/OFF.

When imaging a radiographic image, during irradiation with externalradiation (X-rays) OFF signals are output to the eighth scan lines G8and each of the TFT switches 4 a is switched OFF, and OFF signals areoutput to the ninth scan lines G9, switching each of the TFT switches 4b OFF. The charges generated in a semiconductor layer are accordinglyaccumulated in each of the charge storage capacitors 5.

When reading an image, for example a still image, ON signals are outputin sequence one line at a time to the eighth scan lines G8, switchingthe TFT switches 4 a in each of the pixels 200N. On the other hand, forexample when reading a video image, ON signals are output in sequenceone line at a time to the ninth scan lines G9, switching ON the TFTswitches 4 b of plural pixels in pixel groups, described later, and ONsignals are output to specific eighth scan lines G8 to switch ON the TFTswitches 4 a in the pixels 20. The charges accumulated in each of thecharge storage capacitors 5 are thereby read as electrical signals, anda radiographic image is obtained by converting the read electricalsignals into digital data.

The radiation detector 442 is equipped with variable gain pre-amplifiers(also referred to as charge amplifiers or integrating amplifiers) CA1 toCA3 corresponding to one for each of the data lines D1 to D3, asillustrated in FIG. 10. Sample-and-hold (SH) circuits 97A to 97D arealso disposed in the radiation detector 442 at the output side of eachof the charge amplifiers CA1 to CA3. The radiation detector 442 isconfigured with plural data lines disposed in repeating units of datalines D1 to D3, and the plural charge amplifiers are disposed inrepeating units of charge amplifiers CA1 to CA3 corresponding thereto.The charge amplifiers CA1 to CA3 are each configured including anoperational amplifier 92 a with grounded positive input side, acapacitor 92 b connected in parallel across the negative input side andthe output side of the operational amplifier 92 a, and a reset switch 92c. The reset switch 92 c is switched by the control section 150. Theradiation detector 442 is also equipped with a multiplexor 98 and ananalogue to digital (A/D) converter 99.

Note that sampling timings of the sample-and-hold circuit 97A to 97D andselection outputs by switches 98 a to 98 d provided to the multiplexor98 are also switched by the control section 150. In FIG. 10, themultiplexor 98 is configured bundling together 4 pixels into 1. However,there is no limitation thereto. For example, the multiplexor 98 may beconfigured to match the repeating units of the data lines D1 to D3described above, with 3 pixels bundled into 1.

Explanation next follows regarding operation of the radiation detector442 according to the present exemplary embodiment. During imagedetection with the radiation detector 442, OFF signals (for example, 0V)are output from the scan signal control sections 435 a, 435 b to theeighth scan lines G8-1 to G8-5 and the ninth scan lines G9-1, G9-2,applying a negative bias to the gate electrodes of the TFT switches 4 a,4 b. Each of the TFT switches 4 a, 4 b are thereby maintained in an OFFstate.

During image reading, the radiation detector 442 performs imaging in astill imaging mode or a video imaging mode according to instruction froman image processing apparatus 50, as described above. When instructionwas for the still imaging mode, the control section 150 controls thescan signal control section 435 b such that scan signals are output fromthe ninth scan lines G9-1, G9-2 for switching OFF the TFT switches 4 bin each of the pixels 20. The control section 150 also controls the scansignal control section 435 a to apply ON signals for example with avoltage of +10 to 20 V in sequence from the eighth scan lines G8-1 toG8-5 to the gates of each of the TFT switches 4 a in order to switch ONthe TFT switches 4 a in each of the pixels 20. The TFT switches 4 a ineach of the pixels 20 are thereby switched to an ON state in sequencefor each of the pixel rows, charges are read out from the sensorportions 103 by the TFT switches 4 a, and signals corresponding to thesecharges are output to the data lines D.

Thus in the still imaging mode, in the radiation detector 442 chargesignals corresponding to each of the pixels 20 flow in each of the datalines D1 to D3 by pixel row. Image data expressing an image representingradiation irradiated onto the radiation detection element 410 of theradiation detector 442 can accordingly be obtained. The charge signalsare then converted into digital signals in a signal processing section425, and a radiographic image based on the image data corresponding tothe charge signals is generated.

Explanation next follows regarding operation of the video imaging modein the radiation detector according to the present exemplary embodiment,with reference to an operation timing chart illustrated in FIG. 11. Outof the plural pixels 20 in the radiation detector 442 of the presentexemplary embodiment, for example, the gate electrodes of each of theTFT switches 4 b disposed in the 3 pixels P1 to P3 surrounded by adashed line in FIG. 10 are connected to the ninth scan line G9-1. Thegate electrodes of the TFT switches 4 b disposed in the pixels P4, P5out of the pixels P4 to P6 likewise surrounded by a dashed line are alsoconnected to the ninth scan line G9-1.

Similarly, the gate electrodes of each of the TFT switches 4 b disposedin the pixels P7 to P9 are connected to the ninth scan line G9-2 and thegate electrodes of the TFT switches 4 b disposed in the pixels P10, P11out of the pixels P10 to P12 are also connected to the ninth scan lineG9-2.

Here, the pixels P1 to P3 are referred to as pixel group PG1, the pixelsP4 to P6 are referred to as pixel group PG2, the pixels P7 to P9 arereferred to as pixel group PG3, and the pixels P10 to P12 are referredto as pixel group PG4. Note that, while omitted from illustration inFIG. 10, the radiation detection element 410 is also configured fromplural other pixel groups each formed from 3 specific pixels asconfiguring pixels, mutually adjacent to the pixel groups PG1, PG2 etc.Taking the pixel groups PG1, PG2 as an example, these pixel groupsconfigure pixel group repeating units (each of a total of 6 pixels) withthe 3 pixels of the pixel group PG1 (P1 to P3), and 3 pixels made upfrom 2 pixels of pixel group PG2 (P4, P5) and 1 pixel of pixel group PG2(P6). The repeating units include 3 successive pixels in the same pixelrow direction (in this case P1, P4, P5), 2 successive pixels along apixel row direction disposed adjacent in the pixel column directionbelow these 3 successive pixels (in this case P2, P3), and 1 pixeldisposed adjacent in the pixel column direction above these 3 successivepixels (in this case P6). Each of the 3 pixels of the respective pixelgroups PG1, PG2 are disposed such that two adjoining sides of each ofthe pixels are respectively adjacent to 1 side of each of the remaining2 pixels.

In the radiation detector 442 of the present exemplary embodiment,treating the pixels P1 to P6 described above as a single pixel groupunit, the radiation detection element 410 is configured by disposingsuch pixel group units successively along the horizontal and verticaldirections of FIG. 10. In other words, in the radiation detector 442,the pixels P1 to P5 and the pixel P12 are treated as a single pixelgroup unit, and the radiation detection element 410 is configured bydisposing such pixel group units successively along the horizontal andvertical directions of FIG. 10.

When the video imaging mode is instructed to the radiation detector 442,the control section 150 initially controls the scan signal controlsection 435 a so as to output OFF signals from the eighth scan linesG8-1 to G8-5 to each of the gate electrodes of the TFT switches 4 a ofeach of the pixels 20 to switch OFF the TFT switches 4 a of each of thepixels 20.

The control section 150 then outputs reset signals to short resetswitches in the charge amplifiers. For example, as illustrated in (5)and (6) of FIG. 11, reset signals are output to the charge amplifiersCA1, CA2, and the charges accumulated in the capacitors of the chargeamplifiers CA1, CA2 are discharged (reset).

The control section 150 then controls the scan signal control section435 b to output scan signals (ON signals) to the ninth scan line G9-1.Specifically, as illustrated in (1) of FIG. 11, an ON signal is outputfor a specific period of time by the ninth scan line G9-1. The TFTswitches 4 b of the 3 individual pixels P1 to P3 of the pixel group PG1are thereby switched ON. As a result, charge signals of the charges thathave been accumulated in each of the charge storage capacitors 5 of thepixels P1 to P3 are combined inside the radiation detection element 410,and the combined charge signal of these 3 pixels flows out through thedata line D1.

The electrical signal (3 pixels worth of combined charge signal)transmitted by the data line D1 is amplified by a predeterminedamplification in the charge amplifier CA1 for a period of timeillustrated in (7) of FIG. 11 (referred to as the integration periodT1-1), and held in the sample-and-hold circuit 97B. Sampling of thecharge signals is stopped as the integration period T1-1 elapses.

When an ON signal is output by the ninth scan line G9-1 ((1) of FIG.11), the TFT switches 4 b in the pixels P4, P5 of the pixel group PG2are switched ON. As a result, a combined charge signal of chargesaccumulated in each of the charge storage capacitors 5 of the pixels P4,P5 flows out through the data line D2. The electrical signal (thecombined charge signal of pixels P4, P5) transmitted by the data line D2is amplified by the charge amplifier CA2 for a period of time equivalentto the above integration period T1-1 within the integration period T2-1,as shown at (8) of FIG. 11, and held in the sample-and-hold circuit 97C.The control section 150 ends the integration period T1-1 when the outputsignal from the ninth scan line G9-1 has changed from ON to OFF, howeverthe integration period T2-1 is continued, in a state in which the chargesignals can continue to be accumulated and amplified (integrated) in thecharge amplifier CA2.

The control section 150, after switching the output signal from theninth scan line G9-1 to OFF, then, as illustrated in (2) of FIG. 11,controls the scan signal control section 435 a such that the outputsignal from the eighth scan line G8-1 becomes ON. The TFT switches 4 ain the pixels of the pixel row corresponding to the eighth scan lineG8-1 are accordingly switched ON, and the charge signals read out fromthese pixels flow out through each of the data lines. When this occurs,the charge amplifier CA2 is in a state capable of accumulating andamplifying (integrating) the charge signals as described above, howeverthe charge amplifier CA1 is in a non-operational state. Note that in thevideo imaging mode (during binning driving), since there are no signalsflowing through the data lines D3, the control section 150 places thecharge amplifier CA3 in a constant non-operational state, as illustratedin (9) of FIG. 11.

Hence, as illustrated in (8) of FIG. 11, in the integration period T2-1after the period of time of the integration period T1-1 has elapsed, thecharge signal of the pixel P6 of the pixel group PG2 flows out throughthe data line D2, and the charge signal of the pixel P6 is accumulatedand amplified (integrated) in the charge amplifier CA2 connected to thedata line D2. As a result, in the integration period T2-1 the chargeamplifier CA2 adds the charge signal of the pixel P6 to the previouslyaccumulated and amplified (integrated) charge signals of the pixels P4,P5. The combined charge signal of the pixels P4 to P6 are then held inthe sample-and-hold circuit 97C, and sampling is ended as theintegration period T2-1 elapses.

As described above, when an ON signal is output by the ninth scan lineG9-1 and an ON signal is output by the eighth scan line G8-1, similarlyto with the pixel groups PG1, PG2, 3 specific pixels worth of combinedcharge signals are output to data lines in the plural other pixelsfollowing in the row direction from the pixels of the pixel groups PG1,PG2.

The control section 150 continues the above processing, and performsbinning processing for the pixel groups that are adjacent in the columndirection to the pixel groups PG1, PG2 etc. (the pixel groups PG3, PG4in the example illustrated in FIG. 10). Namely, the control section 150,as illustrated in (5) and (6) of FIG. 11, sends reset signals to thecharge amplifiers CA1, CA2 so as to discharge (reset) the charges thathave accumulated in the capacitors of these amplifiers. The controlsection 150, as illustrated in (3) of FIG. 11, controls the scan signalcontrol section 435 b so as to output a scan signal (ON signal) with theninth scan line G9-2. The TFT switches 4 b of the 3 individual pixels P7to P9 of the pixel group PG3 are thereby switched ON, charge signals ofcharges accumulated in each of the charge storage capacitors 5 of thepixels P7 to P9 are combined in the radiation detection element 410, anda combined charge signal for the 3 pixels (P7 to P9) flows out in thedata line D1.

The combined charge signal for 3 pixels is amplified by the chargeamplifier CA1 during the integration period T1-2, as illustrated in (7)of FIG. 11, and is held by the sample-and-hold circuit 97B. Thensampling of the charge signal is ended as the integration period T1-2elapses.

When an ON signal is output by the ninth scan line G9-2, the TFTswitches 4 b in the pixels P10, P11 of the pixel group 4 are switchedON, and a combined charge signal of the charges accumulated in thepixels P10, P11 flows out in the data line D2. The combined chargesignal is amplified by the charge amplifier CA2 for a period of timeequivalent to the integration period T1-2 within the integration periodT2-2, as illustrated in (8) of FIG. 11, and is held in thesample-and-hold circuit 97C. In this case too, the control section 150ends the integration period T1-2 when the output signal from the ninthscan line G9-2 has become OFF, but the integration period T2-2 is notended, and a state continues in which the charge signal can continue tobe accumulated and amplified (integrated) in the charge amplifier CA2.

After the output signal from the ninth scan line G9-2 has become OFF, asillustrated in (4) of FIG. 11, the output signal from the eighth scanline G8-3 is switched ON. The TFT switches 4 a in the pixels of thepixel row corresponding to the eighth scan line G8-3 are therebyswitched ON. When this occurs, the charge amplifier CA1 is not in anoperational state, however the charge amplifier CA2 is maintained in astate capable of accumulating and amplifying (integrating) the chargesignals, as described above. Note that, as described above, in videoimaging mode (during binning driving) signals do not flow in the dataline D3. Consequently, as illustrated in (9) of FIG. 11, the chargeamplifier CA3 is constantly in a non-operational state during binningdriving.

Hence, as illustrated in (8) of FIG. 11, for the period of time of theintegration period T2-2 after the integration period T1-2 has elapsed,the charge signal of the pixel P12 of the pixel group PG4 flows in thedata line D2, and the charge signal of the pixel P12 is accumulated andamplified (integrated) in the charge amplifier CA2 connected to the dataline D2. As a result, in the charge amplifier CA2, during theintegration period T2-2 the charge signal of the pixel P12 is added tothe charge signals of the pixels P10, P11 previously accumulated andamplified (integrated) in the charge amplifier CA2. Then, the combinedcharge signal for the pixels P10 to P12 is held in the sample-and-holdcircuit 97C, and sampling is ended as the integration period T2-2elapses.

When ON signals are output by the ninth scan line G9-2 and the eighthscan line G8-3, similarly to with the pixel groups PG3, PG4, 3, specificpixels worth of combined charge signals are output to data lines fromthe plural other pixels following in the row direction from the pixelgroups PG3, PG4.

By the control section 150 driving the sample-and-hold circuits 97A to97D for specific periods of time, the signal levels of the electricalsignals that have been amplified by the variable gain charge amplifiersCA1 to CA3 are held in the sample-and-hold circuits. The charge signalsrespectively held in the individual sample-and-hold circuits are, afterbeing selected in sequence by the multiplexer 98, converted into digitalimage data by the A/D converter 99. Note that the digital image dataoutput from the A/D converter 99 is stored in sequence in an imagememory 90. The image memory 90, for example, stores plural frames worthof imaged radiographic images as digital image data.

Note that while not illustrated in FIG. 10, when ON signals are outputby the ninth scan lines G9-1, G9-2, similarly to with the pixel groupsPG1, PG2, charge signals summed in 3 pixel units are output to the datalines from the plural other pixels following in the row direction fromthe pixel groups PG1, PG2.

Thus, in the video imaging mode, in the respective plural pixel groupsconfigured by bundles of 3 pre-specified pixels from the plural pixelsconfiguring the radiation detection element 410, the charges accumulatedin the 3 individual pixels are combined (binned) and charge signalscorresponding to the charges combined through binning are output to thedata lines. Then after controlling the ninth scan lines G9, byoutputting ON signals from the odd numbered scan lines (G8-1, G8-3 etc.)out of the eighth scan lines G8 in FIG. 10, the charge signals of theremaining single pixels, in the pixel groups for which 2 pixels worth ofcombined charge signals have already been acquired, flow in the datalines. In the video imaging mode, an OFF signal is constantly outputfrom the even numbered scan lines (G8-2, G8-4 etc.) out of the eighthscan lines G8.

Consequently, in the radiation detector according to the presentexemplary embodiment, 3-pixel binning processing is performed for thepixels of specific pixel groups (PG2, PG4 etc.) by employing the samecharge amplifier to add together and combine 2 pixels worth of thecharge signals out of the 3 pixels configuring each of the pixel groups,and then the charge signal of the remaining 1 pixel using shiftedintegration timings.

Note that, also in the video imaging mode of the radiation detector 442according to the present exemplary embodiment, similarly to in theradiation detector 342 according to the third exemplary embodimentillustrated in FIG. 8, taking the center of gravity of one pixel groupout of the pixel groups configured from 3 pixels as the center, aregular hexagonal shape is formed by connecting together the centers ofgravity of the other pixel groups, and the inter-center of gravitydistances of these pixel groups are all the same as each other in 0.6directions. Thus, in the present exemplary embodiment, even resolutionmay be secured in each of the horizontal, vertical and diagonaldirections in before and after binning. Thus, in the present exemplaryembodiment, unevenness in the pixel positions (the center of gravitypositions of the pixel groups) may be suppressed after binning, enablingeven resolution to be secured in each of the respective directions,similarly to in an image before binning.

Thus in the present exemplary embodiment, since the centers of gravityarrayed before binning, and the centers of gravity arrayed afterbinning, both are in a state in which hexagonal shaped regions formed bythe centers of gravity are arrayed in a honeycomb pattern, processingmay be performed with a similar algorithm when performing pixel densityconversion after binning to when performing pixel density conversionwithout binning. Hence, the algorithm for pixel density conversionprocessing may be commonly employed both before and after binning,without preparing a separate algorithm for pixel density conversionprocessing after binning.

In the present exemplary embodiment, for each of the respectivepredetermined plural pixel groups each configured from 3 pixels out ofthe plural pixels with hexagonal shaped pixel regions arrayed in ahoneycomb pattern in the radiation detector 442, binning process isperformed by simultaneously reading and combining 3 pixels worth ofcharges in the radiation detection element 410 of the radiation detector442. Moreover 3-pixel binning process is performed for specific pixelgroups, by employing the same charge amplifier to add together 2 pixelsworth of the charge signals out of the 3 pixels configuring each of thepixel groups, and then the charge signal of the remaining 1 pixel usingshifted integration timings. Accordingly, in the present exemplaryembodiment, the S/N may be by increasing the amount of charge collected,and may enable application to a video imaging mode demanding a highframe rate as well as application to low sensitivity images generated byirradiating a small amount of radiation.

Moreover, combination of each of the pixels in each of the pixel groupsis determined such that plural hexagonal shaped regions are arrayed in ahoneycomb pattern. Each of the plural hexagonal shaped regions areformed by including inside 1 center of gravity of the region surroundedby the outlines of the pixel groups, and the line segments connectingthe 6 individual centers of gravity present at the periphery of the 1center of gravity. Accordingly, unevenness of the pixel positions (thecenter of gravity position when plural pixels are treated a single pixelclump) after binning in each of the horizontal, vertical and diagonaldirections may be suppressed, and even resolution may be secured in eachof the respective directions, similarly to in an image before binning.As a result, a common integrated circuit (IC) may be employed for pixeldensity conversion before and after binning.

Moreover, when performing video imaging, charges are acquired bytreating each of the pixel groups configured from 3 respective pixels asa single pixel, and binning process is performed by combining thecharges accumulated in each of the pixels configuring each of the pixelgroups. Hence, although the resolution is lower than for a still image,a frame rate of 2 times (a frame duration of ½) that for reading chargesfrom each pixel row may be achieved in the still imaging mode. Moreover,the number of scan lines G9 can be reduced to ½ the number of pixel rowssubject to binning, in comparison to cases in which scan lines G9 areprovided one for each of the pixel rows subject to binning. Namely, thenumber of scan lines G may be greatly reduced in comparison to theradiation detector 342 according to the third exemplary embodimentillustrated in FIG. 8. Moreover, in the configuration of the radiationdetector 442 illustrated in FIG. 10, in comparison to the 5 scan linesG8 required when binning is not performed, the total number of scanlines required for scanning the pixels, including performing scanningwith binning, has previously been twice the 5 lines, i.e. 10 lines.However, in the present exemplary embodiment only 7 lines are required.

In each of the above exemplary embodiments, the hexagonal shaped pixelsof the radiation detection element 410 may include regular hexagonalshaped pixels and substantially hexagonal shaped pixels that have theircorners beveled. Moreover, for example, flattened hexagonal shapedpixels squashed in the top-bottom direction on the page of FIG. 2, andsubstantially hexagonal shaped pixels when viewed in plan view may alsoincluded. Namely, configuration may be made with pixels having hexagonalshaped pixel regions formed flattened such that one diagonal line out of3 diagonal lines passing through the center of each of the pixels isshorter than the other two diagonal lines and the other two diagonallines are of equal length to each other. Thus even though pixels offlattened hexagonal shape are employed, the relationships of the centerof gravity separations and the six horizontal, vertical and diagonaldirections may be maintained before and after binning processing.

In each of the above exemplary embodiments, explanation has been givenof cases in which the present invention is applied to adirect-conversion-type radiation detector 410 employing aradiation—charge conversion material such as amorphous selenium in aphotoelectric conversion layer that absorbs radiation and converts theradiation into charge. However, the present invention is not limitedthereto. For example, the present invention may be applied to anindirect-conversion-type radiation detector equipped with a scintillatorthat converts irradiated radiation into visible light.

FIG. 12 illustrates a simplified example of the radiation detector 42 ofthe first exemplary embodiment applied to an indirect-conversion-typeradiation detector. FIG. 13 illustrates a simplified example of theradiation detector 342 of the third exemplary embodiment applied to anindirect-conversion-type radiation detector. Note that operations of theindirect conversion type radiation detectors illustrated in FIG. 12 andFIG. 13 are respectively similar to that of the radiation detector ofthe first exemplary embodiment and the radiation detector of the thirdexemplary embodiment, and therefore explanation thereof is omitted.

In each of the above exemplary embodiments, a case in which the commonground lines 30 are disposed on the insulating substrate 1, have beendisclosed. However, there is no limitation thereto. For example, thecommon ground lines 30 may be disposed in any layer below the lowerelectrodes 11 as the pixel electrode that collect charges generated inthe photoelectric conversion layer 6. In such case, the common groundlines 30 lowering the irradiation efficiency of radiation irradiatedonto the sensor portions 103 may be prevented.

In the second exemplary embodiment and the fourth exemplary embodiment,cases in which the scan signal control sections (35 a and 35 b, or 435 aand 435 b) are respectively disposed along the column direction to thesides of the radiation detection element (110 and 410) of the radiationdetector (142 and 442), have been described. However, the placements ofthe scan signal control sections (35 a and 35 b, or 435 a and 435 b) arenot limited thereto. For example, in mammography applications, the scansignal control section (35 a and 35 b, or 435 a and 435 b) may beprovided along the column direction at one side of the radiationdetection element (110 and 410), with the other side along the columndirection disposed on the side of the subject's chest wall. In suchcases, two general purpose gate ICs may be employed as the scan signalcontrol section (35 a and 35 b, or 435 a and 435 b) in a layeredstructure (double-layer) with scan lines G extending respectivelytherefrom, or scan lines G extending from a single custom gate IC.

Fifth Exemplary Embodiment

Specific explanation follows regarding an exemplary embodiment in whicha radiation detector (42, 142, 342, 442) of each of the above exemplaryembodiments is applied in mammography performed by tomosynthesisimaging.

FIG. 14 illustrates a schematic configuration of a configuration of animaging apparatus 41 employed for mammography in the present exemplaryembodiment. FIG. 15 is a configuration diagram of a configuration of theimaging apparatus 41 of the present exemplary embodiment during imaging.FIG. 16 is an explanatory diagram for explaining the imaging apparatus41 of the present exemplary embodiment during imaging.

As illustrated in FIG. 14 to FIG. 16, the imaging apparatus 41 of thepresent exemplary embodiment is an apparatus that images a breast N of asubject W with radiation (for example X-rays) when the subject W isstanding in an upright stance. Note that, in the following, the frontside that is near to the subject W when the subject W is facing theimaging apparatus 41 during imaging is referred to as “the apparatusfront side” of the imaging apparatus 41, and the far side that ispositioned away from the subject W when the subject W is facing theimaging apparatus 41 is referred to as “the apparatus back side” of theimaging apparatus 41. Moreover, in the explanation, the left-rightdirection of the subject W when the subject W is facing the imagingapparatus 41 is referred to as “the apparatus left-right direction” ofthe imaging apparatus 41 (see each of the arrows in FIG. 14 to FIG. 16).

The imaging apparatus 41, as illustrated in FIG. 14, includes ameasurement section 500 that is provided to the apparatus front side andis substantially C-shaped in side view, and a base stand section 502that supports the measurement section 500 from the apparatus back side.

The measurement section 500 includes an imaging table 510 formed with aflat plane shaped imaging face 512 that makes contact with the breast Nof the subject W who is in an upright stance, a pressing plate 514 forpressing the breast N between the pressing plate 514 and the imagingface 512 of the imaging table 510, and a holder section 506 thatsupports the imaging table 510 and the pressing plate 514.

The measurement section 500 is provided with a radiation source 31 suchas a tube, a radiation irradiation section 24 that irradiates radiationfor investigation from the radiation source 31 towards the imaging face512, and a support section 507 that is separate from the holder section506 and supports the radiation irradiation section 24.

A rotation shaft 504 supported by the base stand section 502 so as to beable to rotate is provided to the measurement section 500. The rotationshaft 504 is fixed to the support section 507 such that the rotationshaft 504 rotates as one with the support section 507.

The rotation shaft 504 is capable of switching between a state coupledto and rotating as one with the holder section 506, and a state in whichthe rotation shaft 504 is separate and rotates freely. Specifically,gears are respectively provided to the rotation shaft 504 and the holdersection 506 with the gears configured capable of switching between ameshed state with each other and an unmeshed state. Note that switchingbetween transmission and non-transmission of rotation force of therotation shaft 504 can be accomplished using various mechanicalelements.

The holder section 506 supports the imaging table 510 and the radiationirradiation section 24 such that the imaging face 512 and the radiationirradiation section 24 are separated from each other by a specificseparation, and slidably retains the pressing plate 514 such that theseparation between the pressing plate 514 and the imaging face 512 isvariable. Note that the present exemplary embodiment is configured suchthat the position of the pressing plate 514 (the separation between thepressing plate 514 and the imaging face 512) is detectable. For example,a sensor (not shown in the drawings) may be provided to the slidingmechanism of the pressing plate 514, and the position of the pressingplate 514 detected by the sensor. Adopting such a configuration in thepresent exemplary embodiment enables the thickness of the breast Npressed by the pressing plate 514 to be detected.

The imaging face 512 that makes contact with the breast N is formed forexample from a carbon composite from the perspectives of radiationtransmissivity and strength. A radiation detector 542 is disposed insidethe imaging table 510, and radiation irradiated through the breast N andthe imaging face 512 is detected by the radiation detector 542. Notethat the radiation detector 542 in the present exemplary embodiment maybe any radiation detector (42, 142, 342, 442) of each of the aboveexemplary embodiments, and may be selected (changed) by a user accordingto the imaging.

The imaging apparatus 41 of the present exemplary embodiment is anapparatus capable of performing imaging from plural directions withrespect to the breast N as the imaging subject. FIG. 15 and FIG. 16respectively illustrate orientations of the imaging apparatus 41 duringimaging, and positions of the radiation irradiation section 24 duringimaging. As illustrated in FIG. 15 and FIG. 16, imaging is performedwith the support section 507 tilted.

In the imaging apparatus 41, as illustrated in FIG. 16, when imaging(tomosynthesis imaging) is performed from plural directions with respectto the breast N, the rotation shaft 504 is free to rotate with respectto the holder section 506, and only the radiation irradiation section 24moves in a circular arc shape due to the support section 507 rotatingwithout the imaging table 510 or the pressing plate 514 moving. Intomosynthesis imaging, as illustrated in FIG. 16, the imaging positionis moved from an angle α by a specific angle θ each time, and imaging isperformed at N locations P1 to PN for the position of the radiationirradiation section 24.

In the present exemplary embodiment, as a specific example, a diagnosismode and an imaging mode are provided as imaging modes, with these beingselectable by a user such as a doctor. The diagnosis mode is a mode inwhich a user performs rough imaging of the imaging subject for suchpurposes as a diagnosis or diagnosis. As a specific example, in thepresent exemplary embodiment imaging is performed with a specific angleof 1 degree over a range of −10 degrees to +10 degrees. The imaging modeis a mode for performing imaging at higher definition than the imagingof the diagnosis mode. As a specific example, in the present exemplaryembodiment imaging is performed with a specific angle of 1 degree over arange of −20 degrees to +20 degrees. Thereby in the present exemplaryembodiment, when performing imaging to obtain a high definition image,imaging is performed by swinging over a large angle to increase thevolume of data (image data volume).

Explanation next follows regarding operation of the imaging apparatus 41of the present exemplary embodiment. FIG. 17 is a flow chartillustrating a sequence of processing for imaging an image according tothe present exemplary embodiment. When imaging is performed, imaging isexecuted according to an imaging menu in the imaging apparatus 41. Whenthe imaging apparatus 41 is input with an imaging instruction to performCranial and Caudal (CC) imaging, the orientation of the holder section506 is adjusted such that the imaging face 512 is in an upwards facingstate, and the orientation of the support section 507 is adjusted suchthat the radiation irradiation section 24 is situated above the imagingface 512. When instruction is for Mediolateral-Oblique (MLO) imaging,the imaging table 510 is rotated a specific angle, and the orientationof the holder section 506 is adjusted to tilt the pressing plate 514.

At step S200 of FIG. 17, either the diagnosis mode or the imaging modeis set. There are no particular limitations to the setting method, andsetting may be made based on an imaging menu when there is dataindicating which mode contained in the imaging menu. Moreover settingmay be made based on an instruction when a user instructs using forexample an operation panel 44 and an operation input section 54.

A user contacts the breast N of the subject W with the imaging face 512of the imaging apparatus 41. When in this state an operation instructionis given by a user to start pressing, at the next step S202, the imagingapparatus 41 moves the pressing plate 514 towards the imaging face 512,pressing the breast N.

When pressing of the breast N is complete, the user instructs imagingstart using the operation panel 44 of the imaging apparatus 41 and theoperation input section 54 of the image processing apparatus 50. Theimage processing apparatus 50 actuates the imaging apparatus 41according to the instruction to start imaging, thereby imaging aradiographic image.

At the next step S204, determination is made as to whether the imagingmode is the diagnosis mode or the imaging mode. There are no particularlimitations to the determination method, and determination may be madebased on the setting of step S200.

Processing proceeds to step S206 when the mode is the imaging mode. Atstep S206 the radiation amount is determined according to the thicknessof the breast N detected as described above. Due to the radiation amountreaching the radiation detector 42 (passing through the breast N)varying according to the thickness of the breast N, in the presentexemplary embodiment, a correspondence relationship between thethickness of the breast N and the radiation amount irradiated isdetermined in advance. In step S206, the radiation amount irradiated isdetermined according to the thickness of the breast N based on thepredetermined relationship.

At the next step S208, the number of times for imaging is determinedbased on the imaging angle range and the specific angle. As describedabove, in the present exemplary embodiment, as a specific example, inthe imaging mode the imaging angle range is ±20 degrees and the specificangle is 1 degree in order to obtain a high definition image. The numberof individual imaging times is accordingly determined as 40 times.

In the next step S210, the support section 507 is moved to the maximumimaging angle (20 degrees on the left in the present exemplaryembodiment), and the radiation irradiation section 24 moved. Then, atthe next step S212, radiation is irradiated from the radiationirradiation section 24 and the breast N is imaged. Note that, in thisimaging, imaging is performed similarly to imaging with the normalprocessing of imaging processing of the first exemplary embodiment (seestep S104 of FIG. 5). Namely, in order to read out charges from each ofrespective pixels 20, an ON signal is output in sequence one line at atime to scan lines (the first scan lines G1-0 to G1-7 in the firstexemplary embodiment). The respective charge signals accumulated in acharge storage capacitor 5 of each of the pixels 20 is accordingly read,and a radiographic image is acquired by performing normal processing.

In the next step S214 determination is made as to whether or not imaginghas been completed for the number of imaging times determined at stepS208. Determination is negative and processing proceeds to step S216when not complete. At step S216 the support section 507 is moved to theright by the specific angle=1 degree and the radiation irradiationsection 24 is moved before the processing then returns to step S212 andthe current processing repeated. However determination is affirmativeand processing proceeds to step S218 when imaging has been completed forthe determined number of times.

At step S218, the imaged radiographic images (40 times worth) are outputfrom the radiation detector 42 to the image processing apparatus 50.Note that although in the present exemplary embodiment the total numberof times worth of the radiographic images are output from the radiationdetector 42 after imaging has been completed, there is no limitationthereto. Configuration may be made such that a radiographic image isoutput from the radiation detector 42 each time imaging is completed.

At the next step S220, the image processing apparatus 50 reconstructs atomographic image based on the radiographic images obtained from theradiation detector 42. There are no particular limitations to thespecification of the tomographic image reconstruction, andreconstruction of a tomographic image may be performed according to aknown reconstruction method. Note that, in the present exemplaryembodiment, the slice thickness (thickness of the tomographic image)during reconstruction of a tomographic image is predetermined accordingto the mode. In tomosynthesis imaging, generally the larger the angle ofswing the higher the resolution in the depth direction, and the moredetailed the data that can be obtained in the depth direction. In thepresent exemplary embodiment, more detailed depth direction data isobtained in the imaging mode due to imaging with a larger angle of swingin the imaging mode than in the diagnosis mode. Reconstruction isaccordingly performed when imaging in the imaging mode with a thinnerslice thickness than in the diagnosis mode. Note that, the slicethickness may be thinner in the imaging mode than in the diagnosis mode,and specific thicknesses in the present exemplary embodiment are 0.5 mmin the imaging mode and 1 mm in the diagnosis mode. However, there areno particular limitations thereto and, for example, the slice thicknessmay be determined according to the imaging angle. Moreover, there is nolimitation to the above, and the slice thickness may be determinedaccording to user instruction when slice thickness is user instructed.

In the next step S222, after instructing the reconstructed tomographicimage to be displayed on a display 52 of the image processing apparatus50 and on a display section 80A of a display device 80 the currentprocessing is ended.

However, processing proceeds to step S224 when determination at stepS204 is the diagnosis mode. At step S224, the radiation amount isdetermined according to the thickness of the breast N, similarly to asin step S206 of the imaging mode. However, in the diagnosis mode, theradiation amount for irradiation each time of imaging is made smaller,according to the content of binning processing, than in the imaging modein which binning processing is not performed. For example, when binningprocessing is performed with 4 pixels 20 as a pixel group, as in thefirst exemplary embodiment and the second exemplary embodiment, whereeach pixel group is treated as a single pixel, the radiation amount is ¼the radiation amount when imaging by performing normal processing suchthat the radiation amount per single pixel is the same as when normalprocessing is performed. Moreover, when binning processing is performedwith 3 pixels 20 as a pixel group, as in the third exemplary embodimentand the fourth exemplary embodiment, where each pixel group is treatedas a single pixel, the radiation amount is ⅓ the radiation amount whenimaging by performing normal processing such that the radiation amountper single pixel is the same as when normal processing is performed.

In the next step S226, similarly to in step S208 of the imaging mode,the number of times of imaging is determined based on the imaging anglerange and the specific angle. As a specific example in the presentexemplary embodiment, as explained above, in the diagnosis mode, theimaging angle range is ±10 degrees and the specific angle is 1 degree inorder to perform rough imaging. The number of individual times forimaging is accordingly determined as 20 times.

In the next step S228, similarly to step S210 in the imaging mode, thesupport section 507 is moved to the maximum imaging angle (10 degrees onthe left in the present exemplary embodiment), and the radiationirradiation section 24 moved. Then at the next step S230, radiation isirradiated from the radiation irradiation section 24 and the breast N isimaged, and the radiation detector 42 also performs binning processing.Note that imaging and binning processing is performed here similarly(step S106 of FIG. 5). Namely, in order to read out charges from each ofthe respective pixel groups, an ON signal is output to scan lines (forexample to the second scan lines G2 and the third scan lines G3 in thefirst exemplary embodiment) and binning processing is performed treatingeach of the pixel groups as a single pixel. The respective chargesignals of each of the pixels viewed as a signal pixel is accordinglyread and binning processing performed thereon. A binning-processedradiographic image is accordingly acquired in the radiation detector 42.

In the next step S232, similarly to in step S214 in the imaging mode,determination is made as to whether or not imaging has been completedfor the number of imaging times determined at step S226. Determinationis negative and processing proceeds to step S234 when not complete. Atstep S234 the support section 507 is moved to the right by the specificangle=1 degree and the radiation irradiation section 24 is moved beforethe processing then returns to step S230, and the current processingrepeated. However determination is affirmative and processing proceedsto step S236 when imaging has been completed for the determined numberof times. At step S236, similarly to in step S218 in the imaging mode,the imaged radiographic images (20 times worth) are output from theradiation detector 42 to the image processing apparatus 50.

At the next step S238, the image processing apparatus 50 reconstructs atomographic image based on the radiographic images obtained from theradiation detector 42. Similarly to in step S220 in the imaging mode,there are no particular limitations to the specification of thetomographic image reconstruction, and reconstruction of a tomographicimage may be performed according to a known reconstruction method. Notethat as stated above, in the present exemplary embodiment, the slicethickness (thickness of tomographic image) when reconstructing thetomographic images is 1 mm in the diagnosis mode, this being thickerthan in the imaging mode.

In the next step S240, after instructing the reconstructed tomographicimage to be displayed on the display 52 of the image processingapparatus 50 and on the display section 80A of the display device 80 thecurrent processing is ended.

When performing tomosynthesis imaging as in the present exemplaryembodiment, high speed imaging may be performed due to having a smallerimaging angle range and a smaller number of times of imaging in thediagnosis mode for performing rough imaging. Binning processing may alsobe performed. Moreover, due to having a smaller radiation amount forirradiation when performing binning processing, more specifically due tocontrolling the radiation amount per pixel group (treated as one pixel)to be the same amount as the radiation amount per pixel in the imagingmode, then radiation dose to the subject W may be reduced. Moreover, inthe imaging mode, a larger amount of data (image data) may be obtaineddue to the imaging angle range being larger (swinging over a largeimaging angle). In particular, detailed data may be obtained in thedepth direction. Accordingly a high definition image may be obtained.

Note that although in the present exemplary embodiment explanation hasbeen given of a specific example with the imaging apparatus 41performing tomosynthesis imaging and applied to mammography, there is nolimitation thereto. It should be noted that the processing for imagingimages and the image display processing of the present exemplaryembodiment may be similarly applied to the imaging apparatus 41performing tomosynthesis imaging to other sites.

Moreover, in the present exemplary embodiment, although explanation hasbeen given of a case in which instructions related to imaging are givenby a user employing the operation panel 44 of the imaging apparatus 41and the operation input section 54 of the image processing apparatus 50,there is no limitation thereto. For example, configuration wherein auser performs instruction employing a separately provided device such asa console.

In addition, the configurations, operations and the like of theradiation imaging system, the radiation detector, the pixels and thelike that were described in the present exemplary embodiment areexamples, and may, of course, be changed in accordance with thesituation within a range that does not deviate from the gist of thepresent invention.

Further, in the present exemplary embodiment, the radiation of thepresent invention is not particularly limited, and X-rays, γ-rays or thelike can be used.

1. A radiographic image detector comprising: a detection sectionincluding a plurality of pixels having hexagonal shaped pixel regionsarrayed in a honeycomb pattern, each pixel including a sensor portionthat generates charges according to irradiated radiation, a firstswitching element that reads out the generated charges, and a secondswitching element that reads out the generated charges; a plurality offirst scan lines, disposed one for each of a plurality of pixel rowsconfigured by a plurality of the pixels adjacent to each other along arow direction, that are connected to a control terminal of the firstswitching element in each of the pixels of the corresponding pixel row;and a plurality of second scan lines, disposed one for each of aplurality of pixel groups each configured by a combination of a specificnumber of mutually adjacent pixels out of the plurality of pixels, thatare connected to a control terminal of the second switching element ineach of the pixels in the respective pixel group so as to combine andread generated charges by pixel group unit, wherein the specific numberof pixels are combined such that, when a plurality of hexagonal shapedregions are placed adjacent to each other, the plurality of hexagonalshaped regions are arrayed in a honeycomb pattern, wherein each ofhexagonal shaped regions are formed by including one out of a pluralityof centers of gravity of the plurality of pixel groups at the inside andline segments connecting together 6 individual centers of gravitypresent at the periphery of the one center of gravity.
 2. A radiographicimage detector comprising: a detection section including a plurality ofpixels having hexagonal shaped pixel regions arrayed in a honeycombpattern, each pixel including, a sensor portion that generates chargesaccording to irradiated radiation, a first switching element that readsout the generated charges, and a second switching element that reads outthe generated charges; a plurality of first scan lines, disposed one foreach of a plurality of pixel rows configured by a plurality of thepixels adjacent to each other along a row direction, that are connectedto a control terminal of the first switching element in each of thepixels of the corresponding pixel row; a plurality of second scan lines,disposed one for each of the plurality of pixel rows, that are splitinto a plurality of line-groups and are connected to control terminalsof the second switching elements of the pixel groups belonging to eachrespective group such that, when combining and reading charges from aplurality of pixel groups each configured from a plurality of adjacentpixels in the plurality of pixel rows, charge signals corresponding tocombined charge amounts read out from the respective plurality of pixelgroups are transmitted through different respective data lines; and aplurality of data lines, disposed so as to respectively intersect withthe plurality of first scan lines and the plurality of second scanlines, that transmit first charge signals corresponding to charges readout by the first switching elements in each of the plurality of pixels,and that transmit second charge signals corresponding to the combinedcharge amounts read by the second switching elements of the respectiveplurality of pixel groups.
 3. The radiographic image detector of claim2, wherein, when each of the plurality of pixel groups is configuredfrom 3 pixels, control terminals of the second switching elements ofeach of the pixels in respective of the plurality of pixel groupsalongside each other in a row direction are respectively connected tothe second scan lines, and adjacent scan lines are commonly connected asa single line-group.
 4. The radiographic image detector of claim 3,wherein the 3 pixels are 3 pixels disposed such that two adjoining sidesof each of the pixels are respectively adjacent to one side of each ofthe other two pixels.
 5. The radiographic image detector of claim 2,wherein, when the plurality of pixel groups are each configured by 4pixels, the second scan lines are commonly connected in a line-groupconfigured by an adjacent pair of the second scan lines, each pair ofthe second scan lines being configured by a second scan line connectedto control terminals of the second switching elements of 3 individualpixels in a plurality of respective pixel groups alongside each other inthe row direction, and the second scan line connected to the controlterminals of the second switching elements of one individual pixel ineach of the plurality of pixel groups.
 6. The radiographic imagedetector of claim 5, wherein the 4 pixels are configured by 4 pixelsmade up from 3 pixels disposed such that two adjoining sides of each ofthe pixels are respectively adjacent to one side of the other 2 pixelsout of the 3 pixels, and by 1 pixel disposed such that two adjoiningsides are respectively adjacent to one side of 2 pixels out of the 3pixels.
 7. The radiographic image detector of claim 2, wherein thesecond switching elements connected to the plurality of second scanlines are controlled as blocks with shifted timings for each of theline-groups.
 8. The radiographic image detector of claim 2, whereincombinations of the pixels configuring respective pixel groups aredetermined such that, when a plurality of hexagonal shaped regions areformed adjacent to each other, the plurality of hexagonal shape regionsresults in a honeycomb pattern array, wherein each of the hexagonalshape regions are formed by including inside one center of gravity of aregion surrounded by an outline of the plurality of pixel groupsconfigured by the respective 3 pixels or the respective 4 pixels, and byconnecting together 6 individual centers of gravity present at theperiphery of the one center of gravity.
 9. The radiographic imagedetector of claim 2, wherein the hexagonal shaped pixel regions areformed as regular hexagonal shapes.
 10. The radiographic image detectorof claim 2, wherein the hexagonal shaped pixel regions are formed asflattened hexagonal shapes.
 11. The radiographic image detector of claim10, wherein the hexagonal shaped pixel regions are formed flattened suchthat one diagonal line out of 3 diagonal lines passing through thecenter of each of the pixel regions is shorter than the other twodiagonal lines and the other two diagonal lines are of equal length toeach other
 12. The radiographic image detector of claim 2, wherein theplurality of data lines are laid out bent along one portion of thehexagonal shaped pixel region periphery.
 13. The radiographic imagedetector of claim 2, wherein the sensor portions includes asemiconductor film that receives irradiation with the radiation andgenerates charges, and wherein, the charges are accumulated in a storagecapacitor provided in each of the plurality of pixels and the chargesaccumulated in the storage capacitor are read by the first switchingelement and the second switching element.
 14. The radiographic imagedetector of claim 2, wherein the sensor portions includes a scintillatorthat converts the radiation that has been irradiated into visible light,and wherein, after the converted visible light has been converted intocharges by a semiconductor layer, the charges are read out by the firstswitching element and the second switching element.
 15. The radiographicimage detector of claim 13 further comprising, a plurality of commonlines that connect together one electrode of each of the storagecapacitors and that fixes the electrodes to a specific electricalpotential.
 16. The radiographic image detector of claim 15, wherein theplurality of common lines extend between the plurality of data lines ina straight line shape or in a substantially straight line shape.
 17. Theradiographic image detector of claim 16, wherein the plurality of commonlines are connected to the plurality of data lines through the storagecapacitors, the first switching elements and the second switchingelements.
 18. The radiographic image detector of claim 17, wherein theplurality of first scan lines, the plurality of second scan lines, theplurality of data lines, the plurality of common lines, the firstswitching elements, and the second switching elements, are disposed at alower layer side of the sensor portions.
 19. A radiographic imagingapparatus comprising: the radiographic image detector of claim 2; and aradiation irradiation section provided facing the radiographic imagedetector and that irradiates radiation onto an imaging subject above theradiographic image detector, wherein a radiographic image is imaged withthe radiographic image detector.
 20. The radiographic imaging apparatusof claim 19, wherein the radiation irradiation section irradiatesradiation onto the imaging subject from each of a plurality of differentimaging angles.
 21. A radiographic imaging system comprising: theradiographic imaging apparatus of claim 19; and control section thatinstructs the radiographic imaging apparatus to perform imaging of aradiographic image, and that acquires a radiographic image from theradiographic imaging apparatus, wherein the control section includes,switching section that, based on an external instruction, switchesbetween a first radiographic image acquisition mode that acquires afirst radiographic image configured from image data in single-pixelunits of a radiographic image detection device, and a secondradiographic image acquisition mode that acquires a second radiographicimage configured from image data in multi-pixel units of theradiographic image detection device.
 22. The radiographic imaging systemof claim 21, wherein, when instructed to perform imaging to acquire thesecond radiographic image, the control section controls the radiationirradiation section such that the radiation amount irradiated onto theimaging subject is an amount according to the multi-pixel unit andsmaller than when imaging to acquire the first radiographic image.
 23. Aradiographic imaging system comprising: the radiographic imagingapparatus of claim 20; control section that instructs the radiographicimaging apparatus to perform imaging of a radiographic image, and thatacquires a plurality of radiographic images from the radiographic imagedetector that have been imaged by the radiographic image detector ateach of the imaging angles; and tomographic image generation sectionthat generates a plurality of tomographic images reconstructed withreference to a detection face of the radiographic image detector basedon the plurality of radiographic images acquired by the control section;wherein the control section includes, switching section that, based onan external instruction, switches between a first radiographic imageacquisition mode that acquires a first radiographic image configuredfrom image data in single-pixel units of a radiographic image detectiondevice, and a second radiographic image acquisition mode that acquires asecond radiographic image configured from image data in multi-pixelunits of the radiographic image detection device, and wherein theradiation irradiation section has a range of image angles forirradiating radiation onto the imaging subject that is larger whenimaging to acquire the first radiographic image than when imaging toacquire the second radiographic image.
 24. The radiographic imagingsystem of claim 23, wherein the thickness of the tomographic imagegenerated by the tomographic image generation section based on the firstradiographic images is thinner than the thickness of the tomographicimages generated based on the second radiographic images.